You didn't ask ME, but my preference for the 285/75 over the 295/70 is the 285/75 will be a TALLER tire while just a hair skinnier. (Remember the first number is the width, the second number is the aspect ratio or height of the sidewall expressed as a percentage of the width.) I don't want to start a debate about skinny vs. wide and such - it's mostly personal preference. But most proponents of a skinnier tire will talk about less clearance issues, less rolling resistance, better ice / slick condition traction, and preference for the 'tall skinny' look as opposed to shorter and wider.
285 * 75% = 213.75mm high sidewall
295 * 70% = 206.5mm high sidewall
The 285 has a 7.25mm larger sidewall.
7.25mm sidewall x 2 sidewalls is a 14.5mm height difference (academically) between those sizes with the 285 being taller. 14.5mm is a little over 1/2 an inch. (Take the measurement in millimeters and divide by 25.4.). So, overall, 285/75's may be about a 1/2" taller than 295/70's. Actual measurements of course vary by manufacturer.
The 295 is 10mm wider than the 285. 10/25.4 = 0.39". So a 295 may be about 3/8" wider than a 285.
Sorry...I geeked out on us a little bit there.