Fare Difference

I haven’t flown Jet Blue in years. I’m looking at a LGA or JFK to FLL flight. I see 3 fares. The plane is an A320. I was looking at Blue Extra- but someone please clarify that all that gets me is priority boarding. Otherwise, it appears as if the whole flight is economy and if I wanted extra legroom I pay for more for that! I searched the website for answers, but I can’t find the information I desire.

My alternative is Delta- more expensive but I get a better seat.

Thanks in advance for clarifying this.