If the source material is interlaced and there is no de-interlacing performed you will notice horizontal lines across your screen.
Now regarding the type of deinterlacing being used, you have to be more specific. Do you use software deinterlacing or hardware? If you are using hardware are you using your GPU for it? and if yes then which GPU, cause they are using different methods of deinterlacing but in most cases will output the same PQ results.