...how do you make sure the "less easy" one doesn't feel hard-done-by? I'm sure 6yo DS1 is feeling a bit got-at, his behaviour hasn't been brilliant lately, probably due a lot to heat and end-of-term tiredness, but he is generally oversensitive, not that great with social skills and has been going through a very whingy/whiny stage. DS2 (4yo) has always been more easygoing and just gets on with life so needs less intervention.
I do have the same standards of behaviour for both of them (age appropriate obviously). I don't want DS1 to end up resentful or like the "naughty" brother (but nor do I want him to think he can get his own way all the time or get away with unacceptable behaviour!). Any tips on how to balance things?