A)Honda has better gas mileage
B)The odyssey is better made and can handle the wear and tear of kids much better
C)You usually get more bang for the buck with an odyssey. Especially if you are comparing an ex to a sienna le
D)The outside of the sienna is definitely more appealing and it is a bit shorter and a bit less wide. However, the interior trim and finish of the oddysey is better
D)The backup camera and audio system is much better on odyssey and you can only get comparable back up camera on the sienna if you go upmarket or as part of a package.
If leasing:
a) Honda has a proven damage waiver and is inclusive in the lease toyota is only gotten through a third party provider and tacks on 10-20 dollars per month(also provider might not be around when lease is up)
b)honda has gap insurance built in toyota you usually have to provide for or build into the lease
C)Honda is basically the only company left that has no lease end disposition fee and you can just give back the car as is. Toyota charges a $400 dollar fee at lease end if you do not purchase your vehicle or lease or purchase a new toyota/lexus at the end of contract.
P.s. If you are willing to take a chance Chrysler might save you alot but many people have spent significant and multiple times with repairs by the dealership even on short term leases.
Whichever you choose they are both good choices and may Hashem give you Hatzlacha wherever you may go