Navy planes, like the F-14 and F-18, have stronger structures, as well as other things like folding wings that make them suitable for use on crowded carriers and doing much of their flying over water.
The F-4 was originally a Navy design, so it could adapt to a land based role. It would be difficult to do the reverse.
Airframe has to be heavier to support larger landing gear and the massive stresses of landings and arrests (snagging the cables with tailhook). Carrier landings are controlled crashes, pilot literally flies into the deck at a shallow angle and then throttles up the engines in case tailhook misses cables (so he can fly off and try again).
USAF landings are much calmer, you would probably pull the tail right off an F-16 if all you did was put a hook on it, the whole frame has to take the stress of having the hook snatch the cable and stop the aircraft while the engines are opened up to get it airborne again in case you miss. There's no time to react and throttle up if you miss, watch carrier landings and you'll see the engines straining against the cable for a short time after capture until the pilot knows he's got the cable.
The landing gear is totally different from land based aircaft, it has MUCH more shock absorbing ability and travel to survive the carrier landings.
Essentially what this means is that you need two types of aircraft, a Navy design would carry way too much unneeded weight in the frame and landing gear to use it from ground bases, the weight would be better spent in fuel, armaments, or left off entirely for maneuverability.