piano chord
Bsus4
B1E4F♯5
The third replaced by the fourth, which leans on the third it is standing in for.
What is true of it
Bsus4 is B, E and F♯ — 1, 4 and 5 counted from B.
These are also the notes of Esus2/B. Which name is right depends on what is underneath and what came before — the notes alone do not decide.