Is this show based on the real life 'The Unit' also known as CAG/Delta?

Yes it is.. Loosely

It never mentions delta force in the show, but it is "delta force"..they just refer to themselves as the unit. The premise of the show was inspired by the book "Inside Delta Force" by Eric L. Haney. Its a good book and the show does a pretty good job of reflecting back the mystique of the unit in the first 2 seasons. Season 3 is still decent, but I think Eric Haney left the show as an adviser during season 3 and it shows. Season 4 is pretty terrible in my opinion.

Accurate or Inaccurate, there is no 'loosely' about it, The Unit is entirely based on the premise of Delta. When Col. Ryan is looking at getting a star, it is very much implied that he would be taking over JSOC. There are many other corrections as well. When inducting Bob in the beginning of the series they constantly allude to Delta not in name yet still very directly, almost in a non-verbal sense.

No, the actual name of the unit is not mentioned. It is loosely based on Eric Haney's book "Inside Delta Force". If you read the book then you'll be able to identify which episodes are based on his experiences.