Dual tuner.

In the simplest case, you have a dual tuner. This is able to convert signals from two different sources (usually aerial and cable) into images!

Twin tuner.

With a twin tuner, it's not so much about the sources, but more about the possibilities: It can receive two channels simultaneously and thus, for example, show a film while another one is being recorded in the background!

I think it's the same thing, what I can say is that you can record up to 3 programmes at the same time, only from a coaxial source (DTT, Cable).

Hello gheini
Have a look at "https://www.giga.de" where the difference is explained. It is not the same on this page! It serves different purposes.
Greetings Wolfgang

Yes, it's the same thing!