What is the difference between frottage versus dipping?

[y238992]

Is it possible for a man to be unaware of penetration while in an upright position?
Consider this scenario: both individuals are in the shower, with the woman vigorously rubbing the front ofher soapy body against the man (man's body is also soapy). While frottage, or non-penetrative rubbing, is likely, it seems implausible for the man to be completely unaware if the tip of his penis had at least partially penetrated the vulva in such a position. The sensitivity of the glans (tip of the penis) and the distinct sensation of penetration would generally make such an occurrence noticeable to the man.

To put it in another way, during frottage, the urethra (upper tip) of the penis press against the lips of the vagina but does not go in. That is not dipping, right?

[2Fast4Lust]

And what difference does it make whether it's dipping for frottage?...