There is a big difference between the type of accompaniment guitarists do in different styles of music. In pop and rock, the rythm guitar is often heavy-handed, using big chords and lots of effects, whereas in jazz it is more subtle. In jazz, you are usually trying to make your part fit into some available space in the music so that the sound in the end makes up a kind of mosaic. In pop and rock, on the other hand, you can be part of a brick wall. Throw a brick into a jazz tune, and you can expect some hostile looks from your fellow band members, the pianist in particular. I am amazed at how often amateur guitarists wildly overplay their parts. Tell a guy with a Strat that the song starts in F, and chances are you get to hear a big bar chord, played frantically, immediately after the count-in.
I am dividing accompaniment into three groups, Strumming, Plucking, and Crunching. At this point only one section is available, on Strumming.
Strumming. You play everything with the pick. It is rythm backing as much as it is a harmony supplement. Use it for pop, rock, and funk but think twice (actually, think twice twice) before applying it to a jazz tune.
Plucking. It is a piano-type backing where voicings, mainly sparse, are carefully figured out. In addition to the pick you use the fingers on your right hand. The result is very versatile, and can be applied to almost any style of music. It is particularly suitable for jazz.
Crunching. Might also be referred to as 'riffing'. Includes signature licks and attention-grabbing themes that makes up a recognisable part of a song. The sound is often spiced up with distortion and plenty of other effects.