What's the difference between an I4 snd a V6 engine?

What's the difference between an I4 snd a V6 engine? I'm looking at used Honda and Toyota SUV cars online, specifically Honda CR-V, Toyota RAV4, 4Runner and preferably AWD, or FWD, 4WD, whatever… My last car that died, was a '95 Honda Accord which I believe had a V6 engine but could be wrong. But now when looking at these SUV cars online, a lot say I4 which I have NO CLUE about. Any help would be greatly appreciated! To give you an FYI of my driving, I do admit to driving a little over the speed limit. I do not only highway but city driving too and also hope to do driving in other types of terrain like rocky areas or snow… So details please, what is the difference between the two?
Added (1). I4 AND a V6 engine… Not snd a*
Added (2). What would you recommend given my FYI on my driving, given I'm a little bit of a speeder LOL and the types of areas I'd be driving in?

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