Well I thought I could look online and find a nice explanation with drawings and such. But didn't find any after a short search.
OK a standard hitch works on 95% or more of modern trucks and trailers. Slider hitches actually let the head slide on rails--side to side. That is useful for older trailers that do not have a rounded front end and for short bed trucks. A standard hitch head is fixed and does not side around tho it will swivel.
So unless you are getting a fairly old rv then a standard hitch is probably all you need. Even with new RVs some people like sliders with a short bed truck but most seem to feel that you are fine without one if you are careful.
Unless you are getting a new truck and get it with 'hitch prep', which you should, then you'll have to get rails installed under the truck bed to attach the hitch to. If you have a prep package then you need to buy a hitch designed to use that setup.
I never had rails installed but I think the rails plus installation should run in the $200 range plus/minus. Rails can leave the bed of your truck obstructed when the hitch is removed. The prep packages leave a nice flat bed.
Be warned that these hitches weigh around 200 pounds, sliders more. Look on etrailers.com for more info.
