AUZ is a laterite, CZN is sulphide.
http://users.monash.edu.au/~gmudd/files/2009-CMS-01-Nickel-Sulf-v-Lat.pdf
(If link doesn't work, google laterite vs sulphide nickel)
Laterites are cheap to mine but expensive to process. Sulphides can be expensive to mine but are cheap to process.
The main laterite hopefuls (CLQ, ARL, AUZ, GME etc) are a long way ahead of CZN. They are all fairly close to ready to mine,
if and only if they can get funding. CLQ looks the most likely to get funding, hence why it has a market cap of $950M and the rest are a long way behind. Personally I think ARL has the most to gain from the current market cap from the laterite hopefuls (this doesn't mean it's the most likely to get to production in the current cycle or anything else - just market cap appreciation).
CZN has found something, but we don't know how good it is as the deposit seems to be a bit complex. That said, it'd only take one good hit to send this up by a factor of 10 (or one bad round to send it down by 50%+). The chances of that hit? Up to you to decide.
With all that being said, and not trying to be patronising (because you're an adult and can spend your money as you wish), if you don't know 90% of this stuff already you shouldn't be putting your money in CZN or AUZ shares, because you're gambling and the ASX is rigged against small gamblers.
