A cnidocyte is known to be a type of cell that is placed inside the cnida. The nematocyst, on the other hand, is one part of the cell and this is something that you can find inside the cnidocyte. The cnidocyte is known to be very effective in making sure that different organisms will be able to get their prey easily through the venom that they are able to produce.
The nematocyst will work just like a trigger. It will make it possible for a sharp structure to penetrate the prey when it is needed. These two can work well together in making sure that the right prey will fall to the hands of the organism that would use them both.