GPH - Gallons Per Hour. This is the flow rate of a dripper and they are all labled by this
Pressure Compensating or "PC" - This is a dripper which can control the flow better at a wider range of pressure.
Non-compensating - well the opposite of PC, the flow rate is not as well controlled as a PC dripper.
Non-Draining - Once the water is turned off and the pressure drop in the system to a certain level this dripper will not let out any more water until the pressure increases / water is turned back on. Keeps a system from draining out all the water in the pipes once turned off
Check-valve - This keeps a dripper from sucking back in any debris once the system is turned off. A system when turned off can drain out at the lowest end, when this happens it creates a vacumn within the lines causing drippers to suck back in air or dirt. This type of dripper will not allow this.
Take-apart - Exactly what it says you can open these / take them apart. This can be handy if you run dirty water and dripper clog up. We would suggest getting the proper filtration to prevent this but some locations / situations this is not available.
Stake mounted - Drippers made with a stake attached to help cut down on labor during installation.
Adjustable - Yes you can adjust the flow yourself. Maybe not the most accurate in flow but sometimes on smaller systems its the right thing.
Multi-outlet - Dripper with more than one outlet. sometimes called drip manifolds.
Drip Tape - Not really a dripper but a tube with drippers inside it. It is thin walled and when not filled with water it empties and lays flat. Vegetable row crops are the application for this.
Dripperline or Drip Line - A normal type poly tube in a 1/2" size that has drippers installed inside of it during manufacturing. Flow rates and spacing of the dripper varies.