The main difference between tennis shoes and running shoes is that tennis shoes are made with harder materials to hold up to the activities of tennis.
The running shoes are lighter in weight and made softer so it's more comfortable to run in running shoes.
Running shoes are essentially sneakers or just regular shoes even though some people including myself sometimes just refer to all shoes such as sneakers and running shoes as tennis shoes.
So essentially running shoes are just softer and weigh less than tennis shoes do.
Tennis shoes and sneakers are pretty similar to each other but they are different.
Sneakers and running shoes are basically simple shoes that are made with rubber soles and a canvas topping.
Tennis shoes are sneakers made with the same thing basically but are made much more durable and harder to hold up to playing tennis.
That is why shoes are called Tennis shoes so if you're playing Tennis you really want to buy Tennis shoes and if you're just running or walking then regular sneakers or regular shoes would be okay.
But you can run in Tennis shoes or walk in Tennis shoes as well.
I always called them Tennis shoes when I was a kid even though I never played tennis.
I guess the name just stuck with me and it's what my parents called them as well.