LA is much more positive. E.g. instead of taking something away from the child, they suggest sticker charts, i.e. the child is rewarded and good behaviour is reinforced.
Also, the "experts" are wired up with mikes to the parents, and not physically present all the time. They coach the parents and help them to deal with situations rather than intervening. This empowers the parents as they really see that they can deal with situations, rather than the undermining intervention of SN.
LA has "time out" rather than a naughty step. It looks fairly similar but it is more about cooling a child (and a situation) down. The naughtly step/spot always smacks slightly of punishment to me.
LA's philosophy is that kids will always respond positively to boundaries, clear instruction and lots of affirming attention from mum and dad. Don't quite see that in SN.
And, the bottom line, LA always seems to have a much more positive outcome. I've only seen 2 SNs but I don't hold out much hope for either family.
Btw, I say all of this, but I'm not yet having to deal with kids of this age. Have a teenage sd and a 5mo ds!!! These are just my observations of the programmes and would be very interested to hear if any of it feels useful/relevant to other people!