Complex sentence: What makes the Tristan motif different in the eyes of many analysts is its duration; in the Beethoven example the E resolves to D in approximately a quarter of the time it takes the G to "resolve" to the A in the Wagner.
Split into simpler sentences: What makes the Tristan motif different from earlier appearances of the same notes, in the eyes of many analysts, is its duration. In the Beethoven example, the E resolves to D in approximately a quarter of the time it takes the G to "resolve" to the A in the Wagner.