What is the difference in meaning?
Machinery is a conglomerate--one of those collective nouns that uses singular verbage.
Machines are plural.
If you are waxing poetic, it might work better to use singular verbs over plural ones.
The visual image of machines, also--gives thought to each and every machine as individually standing out--even though they are called machines in a plural sense. Machinery, on the otherhand, regards all the machines in one place as working together to make up a whole of machines....
Yes, and "machinery" could be used figuratively, in contexts that would not allow the substitution of "machines." For example:
The machinery of his diabolical plan as it unfolded was chilling to behold.
....But you could say, "The machinations of his diabolical plan as it unfolded were chilling to behold!"
(But, then again, we're getting off-subject....)