Am i wrong or arent these different??

So i ordered a liquid post for my cornelius keg that was damaged that looks like this

Well when it came in the mail it looked like this

Looking at them yes the grooves match but the inside is completely different i have one of these already and i always get alot of foam and i thought maybe its the gap from the dip tube to the top of the liquid port which is not the case with the original fitting that has the spring. If anyone has insight on this let me know. I might be wrong i know they are the same post technically but i only get foam with this new kind

The exterior of the post is not important - they have to conform to an industry standard at the important QD fit and seal points, and are interchangeable from a post vs QD perspective. You really haven't run into anything unique.

I would suspect that the poppet valve in your post may not be fully opening. Many posts require specific size/length poppets, and aren't happy with some random combinations. Also the so-called "universal poppets" aren't so universal and often require shortening the poppet spring...

Cheers!