As a cook, lemme tell you a thing about collagen.
That's marshmallows :3
No, like, seriously, gelatin is gotten by breaking down collagen. Collagen is what melts away and then gels up again inside of steaks that makes the difference between a tough and a juicy steak. The connective tissue needs to break down to release the collagen, the collagen needs to break down, and then reform inside the steak as gelatin, (that's when the steak reabsorbs the juices), and that gel matrix inside the steak keeping the fibers separate is what makes for a good bite. That collagen further breaking down and then caramellizing is what makes for the crispy, tasty, outer shell of a well-done or chicago style steak.
There's lots of it in knuckles and joints, and traditionally, that's where we get gelatin from. Boil the knuckles to extract the collagen, and now you can make aspic! Or, mix the jelly with an italian meringue, (hot sugar syrup and egg whites blended together real good), and you're able to solidify and stabilize the meringue at room temperature without drying out, thus keeping bouncy.
And that's marshmallows.
Gelatin is also jello and other gelatin things. Like home-style soft-serve!
In terms of nutrition, you body would break down collagen into the constituent parts the same as gelatin, so they have identical nutritional profiles.
So everytime someone says eating collagen is good, imagine eating marshmallows :) But also, marshmallows are actually a legit source of protein, which is why many protein bars are marshmallow bars with "gelatin" or "collagen" right near the top of the ingredient list. Just because something tastes good doesn't mean it's not good for you :) But it's not, like, magically special or anything.