There are real differences.

Different battery compartment sizes, different mast heights etc.

They do come off the same assembly line, but the Yale can be considered the enconomy version when it comes to fit and finish.
Monotrol controls are sHyster only.

I work for a Hyster dealer, and when i order parts for Yales, I simply pick the Hyster model that is equivelant and order Hyster parts.
Same shematics, same motors, same driveline.

Thigs like covers, pedals, cabs etc are different.
Ergonomics are also different.

Yale is to Hyster what Chevy is to Buick.

Same amazing factory support for both lines.
The local Yale dealer s*cking, doesn't mean the whole line s*cks.

BUT

don't get stuck with a truck that the local turds won't/can't support.