I had sex with one girl with absolutely enormous breasts. I think she said K cups.
There was a difference and the boobs made it.
I met her on a dating site but when we met she noticed quickly that I was checking out her breast. A small breasted girl wouldn’t have noticed it because I would not have done that.
She asked me if I wanted to take a closer look and when I did I spent a long time fondling and kissing her breasts. I wouldn’t have done it with a smaller breasted girl.
She noticed I was super hard and started playing with my dick, a smaller breasted girl would probably have done the same. But she leaned in over me so I could grab her breast and feel it when she was stroking and sucking me. You need big boobs for that.
I grabbed her tits when I was doing her doggy, and she pressed my face between them when she was riding me. You need huge boobs for that.
We finished with my dick between her boobs until I came all over them and her face. That also requires rather big boobs.
Sex with a small breasted girl would have been totally different. Maybe better, maybe worse, but certainly different.