In prewar Lionel land a 262 had a manual reverse switch, a 261 did not reverse at all, forward only. (a 262E had a automatic reverse unit.) The bodies and trim was the same between them.
In a MTH reproduction, they are all the same, PS-2, or 3 they all have the standard electronics. They are just copies of the Lionel engines. A MTH 261 or 262 are going to be the same, maybe the trim is nickel on a 261 and brass on a 262. Hope I didn't confuse you too much.