Are there big difference in the degree of zeal among "fan, enthusiast, maniac, fiend, geek, zealot”? If Yes, what are they in order of the enthusiasm?

I saw the word, “language fiend” in a newspaper article yesterday. I thought I saved the text for the purpose of posting this question, but I didn't, so I can’t remember what the source of it was.

When I saw the word, “language fiend,” it prompted me a question – how a language (computer / music / chess /manga/ cosme, whatever) fiend is enthusiastic about the language (computer / music / chess /manga/ cosme, whatever) in comparison with language (computer / music / chess / manga / cosme) fan, enthusiast, maniac, fanatic,and geek.

In Japanese, we have only two groups of xx-愛好者 (aikosha – lover, or fan) and xx-狂(kyo -maniac) to distinguish the level of interest, zeal, and engagiment in an object. In this regard, we are very simplistic. I think I’m English language enthusiast, but won't be a fiend.

Which of them are considered to be the normal 'lover' level and abnormal 'maniac' level? Are there any other English suffixes to describe __ lover or __ maniac than the above?

Language being what it is, a complete ordering is too much to ask for. Nevertheless, I think they can be roughly grouped. "Fan," "geek," and "enthusiast" are aikosha, with "fan" perhaps the least intense, while "fiend," "maniac," and "zealot" are -kyo. I would add that "fanatic," the etymological root of "fan," is in the severe category.

User867 rightly notes that some terms - I think especially "geek" and "nerd" - also describe a particular mode of appreciation. The enthusiasm of those who paint their bodies in the colors of their favorite team and stand shirtless in the crowd is spoken of differently than that of those who carefully study the statistical performance over time of that team's members and coach. The latter kind is what is meant by a "geek" or "nerd", and thus these terms can be applied to a broad range of intensity.