External differences between 1.8 and 2.2 - none, except as FHW pointed out, the badge on the back
External differences between specs - yep, just the foglights on some models, and (if you look closely) the headlight washers on the Sport and EX
And (as per FHW) the ES comes with sunroof as standard, option on EX
Again, you are correct on the wheels - from a dealer (and possibly as its a lease car), Honda will only let you go up one wheel size - so 16" to 17 on the SE & ES, or 17" to 18" on the Sport and EX
If you get right close up and personal (and picky
) the ES and EX come with rain sensing wipers - not
strictly an external change, but it means there is a small box attached to the inside of the windscreen above the mirror.
Sport is in indeed in name only - perhaps 'SP' might have been a better name choice for Honda
As to the engine - no competition