Is a kegel exercise the same exact thing as "clench and release"?

Yes but there's more: The term kegel refers to pelvic muscles that tighten the pelvic floor. They close the 3 openings: urethra, vagina, and anus. It's good to practice daily both quick squeeze & relax, as well as squeeze & hold (eg. 10 seconds) to optimize all functions of these muscles. Like any muscle regular exercise is necessary otherwise "you'll lose it if you don't use it.".

Kind of: A "kegel" squeeze tightens the muscles you would use 2 stop urine streamor hold gas in. Problem: many women have poor muscle control &can't do the exercises. Our brain wants to squeeze, the muscles don't work, so we squeeze something down there& can make it worse. Pelvic floor physical therapy if available is the best way to go. There are few other damaged muscles we would try to fix on our own.