Here are a few notable examples of variants between versions:
Deuteronomy 32:8, 43
4QDeut j : "When Elyon gave the nations as an inheritance, when he separated the sons of man, he set the boundaries of the peoples according to the number of the sons of God (bny 'l[hym]). For Yahweh's portion was his people; Jacob was the lot of his inheritance .... Rejoice, O heavens, together with him, and bow down to him all you gods ('lym), for he will avenge the blood of his sons, and will render vengeance to his enemies, and will recompense those who hate him, and will atone for the land of his people".
LXX: "When the Most High divided the nations, when he separated the sons of Adam, he set the boundaries of the nations according to the number of the angels of God (aggelón theou). And his people Jacob became the portion of the Lord, Israel was the line of his inheritance.... O heavens, rejoice with him, bow to him, all sons of God. O nations, rejoice with his people and let all the angels of God strengthen themselves in him. For he will avenge the blood of his sons. Be vengeful and render vengeance and recompense justice on his enemies, and recompense those who hate him, and the Lord will cleanse the land of his people".
MT: "When Elyon gave the nations their inheritance, when he divided all the sons of man, he set the boundaries of the peoples according to the number of the sons of Israel (bny yshr'l). For Yahweh's portion was his people, Jacob was the lot of his inheritance.... Rejoice, O nations, with his people, for he will avenge the blood of his servants, and will render vengeance to his enemies, and will atone for the land of his people".
Judges 6:6-11
4Judg a: "So Israel was brought very low because of Midian, and the Israelites cried to Yahweh. Then the messenger of Yahweh came and sat under the oak in Ophrah which belonged to Joash the Abiezrite, while Gideon his son was beating out wheat in the winepress, to hide it from the Midianites".
LXX A: "And Israel was greatly impoverished from before Midian, and the sons of Israel cried out to the Lord. And it came about, when the sons of Israel cried to the Lord on account of Midian that the Lord sent a man, a prophet, to the sons of Israel, and he said to them: 'This is what the Lord, the God of Israel, says: I am the one who made you come up from Egypt, and I led you out of the house of slavery, and I delivered you from the hand of Egypt and from the hand of all who oppressed you, and I drove them out from before you and gave you their land, and I said to you, "I am the Lord your God, you shall not pay reverence to the gods of the Amorite, among whom you dwell in their land." And you have not given heed to my voice.' And an angel of the Lord came and sat under the oak which was at Ephratha, which belonged to Joash, father of Abiezri, and his son Gideon was beating out wheat in a winepress to escape from before Midian."
LXX B: "And Israel was greatly impoverished from before Midian, and the sons of Israel cried out to the Lord on account of Midian. And the Lord sent a man, a prophet, to the sons of Israel, and he said to them: 'This is what the Lord, the God of Israel, says: I am the one who made you come up from Egypt, and I led you out of the house of slavery, and I delivered you from the hand of Egypt and from the hand of all who oppressed you, and I drove them out from before you and gave you their land, and I said to you, "I am the Lord your God, you shall not pay reverence to the gods of the Amorite, among whom you dwell in their land." And you have not given heed to my voice.' And an angel of the Lord came and sat under the terebinth at Ephratha, which belonged to Joash, father of Esdri, and Gideon was his son, beating out wheat in a winepress to escape from before Midian."
MT: "So Israel was brought very low because of Midian, and the Israelites cried to Yahweh. When the Israelites cried to Yahweh because of Midian, he sent them a prophet, who said, 'This is what Yahweh, the God of Israel, says: I brought you up out of Egypt, out of the land of slavery. I snatched you from the power of Egypt and from the hand of all your oppressors. I drove them from before you and gave you their land. I said to you, 'I am Yahweh your God; do not worship the gods of the Amorites, in whose land you live.' But you have not listened to me." Then the messenger of Yahweh came and sat under the oak in Ophrah which belonged to Joash the Abiezrite, where his son Gideon was beating out wheat in the winepress, to hide it from the Midianites."
1 Samuel 10:26-11:1:
4QSam a: "Saul also went to his house in Gibeah. The valient men whose hearts Yahweh had touched went with Saul. But certain worthless men said, 'How will this man save us?' And they despised him and brought him no gift. Then Nahash king of the Ammonites oppressed the Gadites and the Reubenites viciously. He put out the right eye of all of them and brought fear and trembling in Israel. Not one of the Israelites in the region beyond the Jordan remained whose right eye Nahash king of the Ammonites did not put out, except seven thousand men who escaped from the Ammonites and went to Jabesh-gilead. Then after about a month, Nahash the Ammonite went up and besieged Jabesh-gilead."
LXX: "Saul went to his home in Gibeah, and with Saul went the valient men whose hearts the Lord had touched. And some pestilent men said, 'What, will this one save us?' And they despised him and brought him no presents. And it happened about a month later that Nahash the Ammonite went up and encamped against Jabesh-gilead."
MT: "Saul also went to his house in Gibeah. The valient men whose hearts Yahweh had touched went with Saul. But certain worthless men said, 'How will this man save us?' And they despised him and brought him no gift. But Saul kept silent. Then Nahash the Ammonite went up and besieged Jabesh-gilead."
Psalm 22:15-16:
4QPs f, 5/6HevPs: "My strength is dried up like a potsherd, and my tongue melts in my mouth. They have placed me as the dust of death. For a pack of dogs are all around me, a gang of evildoors encircles me. They gouge my hands and feet".
LXX: "My strength was dried up like a potsherd, and my tongue is stuck to my throat, and to the dust of death you brought me down, because many dogs encircled me, a gathering of evildoers surrounded me. They gouged my hands and feet."
MT: "My strength is dried up like a potsherd, and my tongue sticks to the roof of my mouth. And you have laid me in the dust of death. For a pack of dogs are all around me, a gang of evildoors encircles me. Like a lion are my hands and feet."
Psalm 145:13
11QPs a: "Your kingdom is an everlasting kingdom, and your dominion endures throughout all generations. Blessed be Yahweh and blessed be his name forever and ever. God is faithful in his words, and gracious in all his deeds. Blessed be Yahweh and blessed be his name forever and ever."
LXX: "Your kingdom is a kingdom for all the ages, and your dominion is in every generation and generation. Faithful is the Lord in all his words, and devout in all his deeds."
MT: "Your kingdom is an everlasting kingdom, and your dominion endures throughout all generations."
I could post more examples if there is any interest, but you get the idea.