When it comes to tumble drying there are 2 main options which you need to consider and think about before buying. The first being weather you would want a Freestanding or Integrated machine and the second being either you want the dryer to be Vented or a Condenser Dryer.
Freestanding and Integrated
The difference between Freestanding and Integrated is that an Integrated machine is made to be built in to a unit and has a door separate to the tumble dryer attached to it. This gives it a more sleek finish as it will match with the rest of the units but it does leave you more restricted as to where it can go as it will need to be put in a space that is specifically built in to a unit for it. Freestanding on the other hand is just that. It is a machine that stands on it's own (without needing to sit in a specifically built unit) and can be placed wherever you like (as long as it's in reach of a plug socket!)
Vented vs Condenser
Vented and Condenser are the 2 different types of way that the tumble dryer extract the warm damp air from inside the machine to out of it. A Vented dryer will have a venting kit attached to it leading to a vent outside the house which the air will be extracted out of. Due to this it can only be used at times where the machine is located within distance of being extracted outside. For machines that aren't within distance to be extracted out you can use a Condenser machine. Condenser machines convert the damp air in to water which is collected in a tray in the appliance which needs to be emptied manually.