The programs are different with different benefits, but some have said they've gotten benefits at one or the other - like an upgrade at an IC without Amb. That shouldn't be expected though. You can see all the details at the IHG Rewards website.

The Terms and Conditions from the IHG Amb site state:
When staying on Reward Nights, all Ambassador and Royal Ambassador Privileges apply with the exception of upgrades, Club Lounge access (Royal Ambassadors), Mini bar beverages (Royal Ambassadors), free Pay-TV film per stay, 24-hour guaranteed room availability and, 8:00 am early check-in (where a cost is applicable). A Rewards Night booking must be booked under the IHG Rewards Club account of the member for him/her to enjoy the benefits.

I've heard that some people get upgrades and maybe some other things even on reward/point stays, but don't count on it. It just depends.

For the two ICs you've mentioned, search for the discussion just on them. You'll get a lot of info on what people got or can expect. I find those specific discussions very helpful.
Happy travels!