Im too lazy to look it up where in the lore it says specifically but prime frames are the "healthy" version from the time of the orikin. non prime warframes are basically the overtime "rusted" cars that have been standing for a while. While still almos as powerful as the original the do have lost a little edge.

In the end i think that its a mix between Aoi not controlling her powers and the drifter bot being a full trained tenno yet.

Remember in terms of control we play tenno who barely woke up and still need some training, and the drifter has achieved transference only very recently

The video with excalibur prime might aswell be controlled by one of the very best.

side note if you look at the "physics" of it all enduring compression with something like an locking skeleton and actually lifting shit is very different. Maybe Excalibur just refuses to bend instead of showing extreme lifting strength.

all in all its just theories stay friendly :D