What is the difference between missiles

conventional missiles
cruise missile cruise ship dirt cheap
guided missile frigates
land cruise
mid range missile

weapon stats are all listed here: https://www.simcountry.com/cgi-bin/cgip?loadDocument&miDocument=warweapons

As far as I can tell the only ones important are cruise, guided, and mid range.

Mid range are basically just fodder for the defensive helicopters, Cruise with guided are good for punching out garrisons if you need to before taking out the air force.