From a system mechanics point of view, is there a difference? Should there be a difference?
In the interests of simplicity I'd recommend keeping the same system mechanics for any entity gained via thaumaturgy - whether crafted from physical parts, created from ectoplasm, called as an ally, or summoned and bound. The differences are profound as far as the story goes but not mechanically.
Insofar as the system mechanics are supposed to support the story more than the crunch, there should be some difference. We do want mechanics, but we should try to align them with the potential story impact. Ultimately, these things are limited by our imagination, so it comes back down to three questions:
1) What do we get? Powers, skills, ally, etc.
2) How much do we pay? Shifts, stress.
3) How likely will this cause plot complications? Things like the Defects, Demonic Agendas, and other sources of drama.
Spending 23 shifts on a Construct is a different story than spending the same on a Demon or a Troll. They could all look the same on paper, with similar powers, but their Aspects and the GM's take on each one's agenda and attitude will differ widely.
If it makes sense that any Conjured or Summoned option is roughly balanced between "What do we get?" and "How likely will this cause plot complications?" then I would be happy to make everything cost the same, get back to the story, and trust the GM and players to work out the drama between themselves. I feel like I'm spinning my wheels, and I'd be happy to get back on firm land with this so we can get a nice system to use. I appreciate all of your help!