error in xhtml 1.0 strict DTD?

I have possibly found an error in the strict xhtml 1.0 DTD.

Buttons in forms can be set in 2 ways:
<input type="submit" name="action" value="send" />
or
<button type="submit" name="action" value="send" />

Both give the same result. There i conclude that the input-types are only
there for compibilty, so that part is transitional and not strict.

If i'm wrong what's the differents between the two tags?

With best regards,

Dave Mertens
dmertens@ism.nl