lichess.org/training/77294Hey. Why computer answer with Bb1-e4 and not Re1-f1? Its not only quality=2pawns question. But question about position and opportunity.
It is the same: white is losing. When two lines are losing the puzzle just takes one of them.
It seems that white can win a pawn back in all lines after Bxe4 Bxe1 Bf4, so both moves lose about the same amount of material.
Other things being equal, white would rather keep the pawns on e5 and d5/e4, as they deny black's rooks open files to attack through. After Rf1, black wins the e5-pawn and takes control of the e-file.
But the computer evaluations are very close, within 0.1 pawns.
The main point of this puzzle is to find the key move ...Bxf2. The puzzle could stop there, but for clarity one more move is added.