car seat issues

Chantel • First time momma of twins girl's 🤰👭💕 08/09/2018

So I decided that we would buy the big zero to 75 pound car seats for our twins. However I have noticed most people I see out with new burns have the car seats that are detachable from the car base. My question is am I ok with taking my girls home in the car seats I have or do I need to buy the detachable seats? I just want to make sure the hospital will let us take our girls home in the seats we have.