Survival knives is a topic survivalists often disagree on, but a survival knife is really a knife that you use when you need to survive in the wild.
A survival knife can be any knife that you prefer, but because you prefer it does not mean its the best survival knife out there. So what makes a knife a great survival knife in my opinion?
Here it is:
A survival knife must be a fixed blade. When you are doing carpentry or need to cut down a tree or need a knife that can hold strength, you need a fixed blade survival knife.
A survival knife should have a nice grip. This is only for comfort but you really do need one that you are comfortable holding and using.
The other thing is this part in the picture below

The part will keep your fingers safe if you need to stab your knife in a tree or whatever. It blocks your hand from sliding onto the blade and cutting your fingers.
Another detail of the knife is that the top part of the blade as in the picture below:

The top part of the blade should NOT be sharp. As you can see on this knife which is my own survival knife the top part looks like its sharp, but its not. Only from the side it looks lie that. A lot of times you need to push hard on your knife when working with wood or something and having a sharp top causes more of a danger than the great idea behind it.