The difference between "forever" and "eternal"
The Hebrew word in both is the same Olam which means "age lasting or
the end of the age. The earth will last until it reaches the end of it's age which
God has established.
EX. 12;14 A feast for the Lord throughout your generation as a statue forever.
Lev.23:41 You shall celebrate it as a feast to my Lord for seven days in the years. It is
a statute forever throughout your generation.