There are 4 main types of modern cloth nappies:
Prefolds - where you have a waterproof cover with a cotton pad-style insert laid inside eg. Real Nappies.
Fitted nappies - where the whole nappy is absorbent but it requires a cover over top, eg Tots Bots.
Pocket nappies - where the nappy has an absorbent fabric outer and a pocket inside where you stuff a pad-style insert in for absorbency, eg. Honeychild or Fuzzi Bunz.
All-in-ones (AIOs) where everything is included in the one nappy - it has a waterproof outer and the absorbency already sewn in (closest to a disposable), eg Itti Bittis or MonkeyDoodlez.
All styles have their pros and cons. You could try a newborn hire kit. That way you could try a selection of styles & brands of nappies on your baby before deciding what you like best. Have a look on www.thenappynetwork.org.nz and there will be a list of local & national hire kits. They are really cheap and give you a chance to try different types of nappies and would be good for the first 6-8wks if you want to use cloth from birth. Going cloth is an investment up front, so you don't want to splash out on a a major supply of one brand only to find you don't get on with it. Different styles/brands fit different babies better. The other thing is you could buy a few preloved off Trade Me to try out first. Although the thought of buying 'used' nappies might not appeal at first there's really nothing wrong with them as long as you give him a hot wash & a rinse with Detol or Canestan when you first get them. I've bought heaps of nappies this way and managed to get a really good newborn stash for a fraction of what it would have cost me to buy them new
As for bulk - it varies between brands/styles. A one-size nappy will be bulkier on a small baby. Probably the trimmest cloth nappy on the market is Itti Bitti D'lish - they come as an all-in-one and a snap-in version.
Hope that helps!
Vic xx