Mf, the human penis is composed of spongy tissue which hardens under pressure full of blood. Muscles are composed of actual muscle which can contract - this is generally the part we humans consume in prey animals. Organ meat is composed of what's termed "smooth muscle".
Of course they're different, it's like saying a squid's tentacle - a muscular hydrostat - works off of blood pressure, they don't, they work off of muscles contracting and interacting with each other