The Top Safety Pick rating can be achieved with an "Acceptable" rating in either or both the newer passenger-side small offset crash result and/or the headlight rating:
https://www.iihs.org/iihs/ratings
The individual vehicle pages at the IIHS show all the sub-category ratings, here is the one on the Odyssey:
https://www.iihs.org/iihs/ratings/vehicle/v/honda/odyssey-minivan
All vehicles have standard stability control and side curtain airbags since around 2012-2013.
In general, frontal crash tests and therefore overall crash test ratings can only be directly compared within the same vehicle class. That is because vehicles that vary significantly in height, weight or weight distribution may perform diffferently crashing head-on than they might in a head-on crash with a very similar vehicle.
For example, consider that the energy in a crash in two top rated small vehicles is rather low, and could be more easily dissipated to prevent injuries in a head-on crash of two small vehicles with excellent crash ratings.
Now, consider two large, rigid truck-based vehicles crashing head-on, the energy is higher due to much larger mass. It is feasible that passengers may not fare nearly as well when two vehicles of this type crash, especially if they have less than good crash test ratings.
Finally, consider a head-on crash between that top small car and even a poorly rated large truck based model. It's quite possible the passengers in the large vehicle might fare better in a head-on crash against a much smaller and lighter model, simply because of momentum and incompatibilty of their chassis/frames.
These are just hypotheticals, of course. The IIHS has some data showing the advantage of mass tends to become less important after 4000 lbs. or so. Weight/mass is also generally not a major factor in side impacts, though vehicle height can be a factor in dissimilar vehicles in a head-on crash.
There are obvisouly a lot of variables that aren't considered by IIHS or NHTSA ratings, so there isn't a clear way to compare vehicles across classes.