5V vs 12V
Usually one of the first questions is which one should I buy?
In general 12V pixels are more popular than 5V.
In a longer answer we need to understand how a pixel works.
Pixels come in 2 main types of voltage in our hobby. The 5V and 12V version. It is always a debate on which one is better. To be honest they both have their advantages.
All pixels actually run on 5 volt DC power. The way a 12 volt pixel works is by reducing the 12 volt power down to 5 volts by adding either resistors or regulators to the chipboard. The 5 volt power is then used to power the pixel LEDs. The 12 volt from the wire then continues down the strand as 12V power to the next pixel.
Here is a 12V Regulated pixel.
This is why you'll see 5 volt pixel looks like it is missing items on the chipboard. It is only because if you are running 5 volt power already it doesn't need to be reduced to power the pixel.
This is a picture of a 5v pixel board. Notice it doesn't have as many components of the previously pictured 12v pixels.
Here are some pros and cons of both.
5 Volt Pixels:
You must power inject more often
Not as readily available
12 volt Pixels
Can run more pixels with less power injection
More Readily Available