EDIT: I have written much longer and more comprehensive Guide to Gaelic to be, the substantive verb bi, tha & the copula is now – you might want to read it instead. :)
No. That’s not correct. It actually is the same difference as in the introduction thread.
There are 2 ‘to be’ verbs in Gaelic:
- bi (whose forms tha, bheil, and eil are),
- and so called ‘copula’: is (which is often shortened to ’s or is completely omitted).
Tha (form of the bi verb) means ‘is’ only for adjectives, prepositional phrases, and adverbs. It tells you:
- what something is like,
- where it is,
- when it was,
- how it is…
It does not tell you what or who something is. For that you need the copula is (which often is omitted, eg. before seo or sin).
- it is bad: tha e dona,
- this is bad: tha seo dona,
- that is bad: tha sin dona,
- it is a dog: is cù e or is e cù a th’ ann,
- this is a dog: seo cù (or: is e seo cù),
- that is a dog: sin cù (or: is e sin cù).
I don’t know the exact syntax of the Scottish copula (I know a bit about it in Irish, and it’s fairly complex), so won’t try to explain its word order, as that’d just be misleading and probably wrong. The point is: you can use tha only when talking about attributes of something (what’s it like) or its whereabouts (where, when, how it is), and you must use copula when directly saying what and who something or someone is.