So the Brotherhood Of Steel of the Capital Wasteland are in the game & what i was really hoping to see them wearing was a set of Hellfire Power Armor that is seen in Fallout 3.

Did the B.O.S discard them or remade them into the T-60's?

The BoS didn't have them in FO3...the Enclave did.

I meant to say after the events of fallout3 i was wondering if the B.O.S ever scavenged whatever Hellfire power armor that was left after the battle for a certain Air Force base & put them to use or just remade them into the T-60's

well there is X0 1 armour only thing you need to do is find a complete set and modify it to your likings on the PA workstation

It's been asked, I think Beth went with the T-60 as it's more advanced than their previous armour but still looks like "BoS"

Well, pc only, but someone seems to be modding it:

http://www.nexusmods.com/fallout4/images/15011/?

Second pic down.

Are these the same BOS unit from F3? They are a big organization I thought they were a different unit.

Yes, they are from Washington, DC (Fallout 3). Maxson took over after Elder Lyons died. He also re-united the Outcasts with the BoS that served under Lyons, to create one big group. They build the Prydwen at Andrews Air Force base. So yea, it's essentially the same BoS chapter that appears in Fallout 3, under different leadership and probably better organized. There are many terminal entries and also dialogues that will tell you this.