String bending with the 1st finger is very different to bending with the 2nd, 3rd, and 4th fingers.

Due to both mechanics and fretboard locations, we never bend the first finger by a whole step. We only ever bend it by half a step (i.e. a semitone, aka one fret). We also usually pull down on a first finger bend. Whereas with 2, 3rd and 4th fingers, we generally push up.

1st finger bend are more subtle, but sound so cool when done well. This technique is essential for anyone serious about learning lead guitar!