The F/A-18 Hornet is the primary tactical aircraft in the Navy fleet. It has taken on the roles of the A-6, F-4, F-14, KA-3, RF-8, and RA-5. It will soon replace the EA-6
The F/A-18 C and D (C version is single seater, D version is two seater) is being replaced by the F/A-18 E and F and is called the "Super Hornet". Besides being about 25% bigger than the earlier non-Super Hornet, it has tremendously improved avionics systems and in a head-on aspect, is much more stealthy. The E&F will replace all C&D Hornets in the USN.
The USMC flies the Hornet also, but they will NOT get E&F Super Hornets. They've decided to hang onto their C&D models until the F-35 becomes available. I'm reasonably sure that all USMC F-35s will be the vertical take off version, and will replace both the AV-8 Harriers and the F/A-18 Hornets in the USMC fleet. USMC also operates some EA-6 Prowlers, but they will be replaced in USN with F/A-18G Growlers, basically a Super Hornet with new advanced versions of the jamming pods already on the EA-6. I don't know what USMC's plan is for replacing their EA-6s.
(Regarding the F-35, which does not yet have a name, there is also a "small wing" USAF version, and a "big wing" USN version. The USN version will also have different avionics than the USAF version.)
Hope this answered your question.