As a native speaker, I would use the word "nonsense" to describe words that were foolish or silly. For example, when a friend is complaining about having to get the whole car repainted because of one small scratch, I might say, "What you are saying is nonsense. Just repaint the scratch". The word "senseless" is often used to describe the extreme actions of people that have no feelings or conscience. For example, when describing a murder or bombing, many people say, "It was a senseless crime". I hope this helps

Nonsense is used more often to explain that facts do not make sense. For example, the news tonight was nonsense, there were no facts in the reporting. Or, I looked at the bookkeepers report and it was nonsense, none of the numbers added up. Senseless is more used to describe a feeling that an event is difficult to understand or did not have to happen. The death of so meaning people in the earthquake seems senseless. Senseless can also be used to explain something is stupid....the kids broke the windows in the old building, this is senseless. Or...Don't be a senseless idiot. Or you lost your senses...She collapsed, senseless, after hitting her head.

I think the major difference between them maybe one is positive and second is negative. Non-sense means no connection or logical progression in the concept for example Stop this nonsense Senseless means Empty of rational connection of thoughts and ideas. For example- Your words are senseless in reality

Nonsense means like bullshit Sensless means like meaningless