I hope that you enjoy your little bundle of fluff... what are you getting?
To answer your question:
Clumping - these clump together when the cat uses it to go to the loo. Easy to clean out with little waste.
Non-clumping - these don't clump when your cat goes to the loo and can mean a lot of waste and fishing around the tray to find all the used bits.
Lightweight - a light litter with no added bits.
Clay - made from pellets of clay, which when wet stick to your cats paws and get trod around your house. Also create lots of dust when filling the tray.
Bio - will biodegrade in a compost bin
wood - made from compacted wood pulp
Paper - made from compacted paper pulp.
Your Cats magazine recently did a survey of all litters available in the UK market.
They looked at all the different types for smell, tracking (how much your cat spreads it around your house on it's paws), dust, efficiency (how long a tray lasts), waste and environmentally friendly.
We used to use catsan, but this was always around our house as it got stuck in Jacks paws, and kicked all over the room from the tray. It is also really dusty when you fill the tray.
The winner of the survey was OkoPlus Cats Best. I tried this and was immediately sold on it. It's made from wood dust compacted. It's treated so that urine and faeces do not smell if left (but you should never leave it in the tray) and also it can be put in a compost bin. It is a clumping litter and is very economical. A bag lasts us about 3 weeks. I recommend you try this one, and I have found that the cheapest place in the UK to buy from is
http://petfoodwarehouse.co.uk/
You should wash out the tray regularly (at least once a week) and replace all the litter at this point. Then just remove the used bits. This will remove any chance of infection from the litter.
I hope that this helps you out...
Good luck with your new friend.
MadCat