Two different versions of Mozilla 1.3.1?

Since I'm running OS 9.1, the last version of Mozilla i can use is 
1.3.1. There appear to be two different versions, though. One can be 
found at:

<http://www.t3.rim.or.jp/~harunaga/mozilla-macos9/>
Unofficial Mozilla for Mac OS 9 (Mac OS Classic)

The other is WaMCom, at:

<http://wamcom.org/>

Are these indeed different versions? If so, what are the differences, 
and is there are reason to prefer one over the other?

TIA
-- 
D.F. Manno
[email protected]
"The work goes on, the cause endures, the hope still lives and the dream
will never die."