There are many key differences between the messiah concept and the Hindu Guru concept. Of course there are also many takes on it ... that of the staunch Abrahamic follower, that of the universalist, that of the staunch Hindu, that of the universalist leaning Hindu, that of the atheist etc., and more. No view is more correct than another, they're all just views.
Some ideas ...
In the messiah concept, it is one and only this one particular messiah that is necessary. So Christians need Jesus, etc.
In the Hindu Guru, concept, the Guru is necessary, but Gurus with that stance say, 'A Hindu Guru is necessary, not 'this particular Hindu Guru is necessary.' or worse .."You need ME'
From the atheist POV, neither is necessary at all. "I can do all this by myself."
Another key and crucial difference is that in many cases within the messiah concept the messiah can do the work for you. "Jesus died for MY sins'.
In Hinduism, you're on your own, and the Guru says, "I can show you the path but you must walk it yourself."
And yes, of course, translations are a problem. When ever someone says, 'I believe this is what he really meant' in regard to scripture, ... well, at least its prefaced by an opinion.