What is the difference between a Trimble ID and Google account

When updating some of the (Native) SketchUp extensions,you sometimes have to log out first and then log back in.
You can sign in with a Trimble ID (TID) or Google account.
But what is the difference exactly ?
I the past, I have created several google accounts with various companies and personal ones etc.
Can I merge them into one TID ( so my bought extensions will be on one account)

When I go to the help page Support - Technical Support | SketchUp Help

I can’t find info.

As far as I am aware, there would be no way to merge them. Trimble will have your Trimble ID stored, and your google ID’s will be attached to your google email accounts.
There are a number of security issues with google accounts, including the recent revelation that marketing partners have been given access so their employees can read your google email (not just scan it for key words).

So the Trimble ID is the way to go.

Models are stored in your Trimble account.

Both accounts are Single Sign-on accounts. These make a relation between your account ID (that is the username) and your authentication secrets. If you use a Google account for authentication, your Trimble “data” account has a reference to the ID that you use to authenticate through Google. It could be possible to convert a Trimble account with Google login to one with Trimble login, but you probably cannot keep both login methods at the same time.

And you know Trimble employees cannot see your models (if you don’t always look over their shoulder)?
Nowadays it is difficult to decide what is better: Centralizing everything to a very trusted authority or keeping things separate. A tradeoff between high security (but high potential loss) and risk (the more distributed, the more likely a breach occurs somewhere but with less damage).