Lesson
White to move. Main line: 1. Nxe5 Qe7 2. Nf3 Qxe4+ 3. Be2
Can White simply take on e5? Yes — but only because after ...Qe7 the knight retreats and the recapture on e4 walks into a development race that favors White: the queen will be kicked with gain of time by Nc3 and d3.
The instructive point is the difference between winning a pawn and keeping it. Black regains the pawn but concedes the initiative; strong players often decline such pawn grabs precisely because of the tempo count.
Try stepping through the replay and counting developed pieces after move five — the material is equal, the position is not.