Components and parts of them

[tkwasnitschka]

Hi,
I have a big 10k image project that falls apart into 1 component of 2 parts.
Part 2 is clearly disconnected from Part 1 and has 22 images, part 1 contains all the others that are clearly internally connected with matches - yet part1 shows me a complex pyramid of smaller parts.
Why is that?
What is the difference between a part and a component in the first place?
Are only "level one parts" disconnected?

I should add that I processed the data set on a cluster of 7 machines. Is this the reason?

Please explain here or expand the reference!
thanks
Tom