"mostly important" or "most importantly"

[Rachel_Liu1019]

I'm a little bit confused with these two phrase: "mostly important" and "most importantly".
Are they both correct?
Do they have the same meaning?

[Mister Micawber]

As sentence adverbials, they mean the same. Here is a usage note from an on-line dictionary:

Both more important and more importantly occur at the beginning of a sentence in all varieties of standard English: More important (or More importantly), her record as an administrator is unmatched. Today, more importantly is the more common, even though some object to its use on the grounds that more important is an elliptical form of “What is more important” and that the adverb importantly could not occur in such a construction. More importantly probably developed by analogy with other sentence-modifying adverbs, as curiously, fortunately, and regrettably.
_________________
Native English teacher at Mister Micawber's

[Rachel_Liu1019]

Thank you very much,Mr. Micawber.

[Mister Micawber]

I'm sorry, but I misread your original post. I think it should read 'most important', not 'mostly important'. The discussion I posted about 'more important' vs 'more importantly' also applies to 'most important' vs 'most importantly'.
_________________
Native English teacher at Mister Micawber's

[Tom]

[Mister Micawber]

It is not a comparative structure. Cf: 'This is the commoner brand of beer.'
_________________
Native English teacher at Mister Micawber's