What's the difference of ContentType and MimeType
I've always viewed contentType to be a superset of mimeType.  The only difference being the optional character set encoding.  If the contentType does not include an optional character set encoding then it is identical to a mimeType.  Otherwise, the mimeType is the data prior to the character set encoding sequence.
E.G. text/html; charset=UTF-8
text/html is the mimeType
; is the additional parameters indicator
charset=UTF-8 is the character set encoding parameter
E.G. application/msword
application/msword is the mimeType
It cannot have a character set encoding as it describes a well formed octet-stream not comprising characters directly.
As far as I know, they are absolute equal. However, browsing some django docs, I've
found this piece of code:
HttpResponse.__init__(content='', mimetype=None, status=200, content_type='text/html')
which surprise me the two getting along each other. The official docs was able to solve the issue in a pratical manner:

content_type is an alias for mimetype.
  Historically, this parameter was only
  called mimetype, but since this is
  actually the value included in the
  HTTP Content-Type header, it can also
  include the character set encoding,
  which makes it more than just a MIME
  type specification. If mimetype is
  specified (not None), that value is
  used. Otherwise, content_type is used.
  If neither is given, the
  DEFAULT_CONTENT_TYPE setting is used.

However, I don't find it elucidating enough. Why we use 2 different naming for (almost the same) thing? Is "Content-Type" just a name used in browser requests, and with very little use outside it?
What's the main difference between the each one, and when is right to call something mimetype as opposed to content-type ? Am I being pitty and grammar nazi?