Female ejaculate may contain a large percentage of urine, but that doesn’t mean that the experience of, or stimulus for squirting and peeing is the same. They’re different. When I have to pee, I feel a fullness in my bladder, go to the toilet, and voluntarily release the urine into the bowl. When I’m getting stimulated during sex under certain conditions, my bladder doesn’t necessarily feel full, and I have an involuntary experience of liquid release. Squirt may be pee (or largely pee), but that doesn’t mean squirting is peeing. They’re qualitatively different.