ok so i have recently been told that i sing from the throat instead of the diaphragm...can someone explain this to me in easier terms...so far as i am concered the air comes from my lungs...any help would be useful

Saying that, is an oversimplification of a rather complex process.

We all sing with our vocal cords, that of course are in the larynx. One problem is how to manage the air that pass between the two cords and makes it vibrate. It certainly comes from the lungs, but to exhale the air in a controlled way (you need that for several thinks, but one quite important is to make it last for long phrases) you need to use your abdominal and chest muscles correctly.

The diaphragm is a strong internal muscle, it is used mainly involuntarily when you breath deep and feel the air like if it were expanding your abdomen) but we do not have so much of a big control on it.

The problem you are being told is probably more related to the use of your head resonators, the "hollowing" of the back of your throat and the correct direction of the air so that your voice is projected with all the volume and sonority needed. i.e in correct singing technique many parts are involved and I am afraid that elaborating more on this could cause still more confusion.

But if you are not singing liric music (say, opera style), it is probably not necessary to project much, as you will be using electronics amplification most of the time. I this case you should produce a rich sound and according to the style you want to have. But you still have to manage your air, as I said above

would that be the same thing as singing through your nose

Having "a nasal sounding" voice is something to avoid, almost at any price. It is considered to be "ugly".

The sound is projected through your mouth, with an open and high placed back of the throat and trying to make the sound resonate in the cavities that exists over the palate (the head sinuses). For this I have been taught to keep open the nasal ways (but not trying the sound go trough them). The jaws also descend to leave a space among your high and low molars.

This is difficult to explain, even personally in front of the teacher.

You can think of a tube or conduit, coming from the abdominal region, through the vocal cords up into the upper back of the throat. There the "tube" has a 90 degree bend towards your mouth.

All this way must be kept open and free. For this freedom, your neck must be kept relaxed, the larynx must not rise in higher notes) and you must produce a king of hollow cavity in the back of the throat, by raising its ceiling.

The correct projection is based on this position, that must become automatic and "normal" when singing lyric music. But I have another teacher that insists that the actual basis of a good projection is to produce a rich tone (one with many harmonics in it). It is what lets you be heard at the back of theatre hall full of people and/or over a full sounding. orchestra.

Sorry that this effort to describe this complex mechanism puts me at the limit of my proficiency in English. I hope I am not being too much confusing.

<Added>

OOPS!
a king of hollow = a kind of hollow

My voice teacher told me that breathing through your diaphragm also helps control how long you hold your notes and your voice cracking while you sing. If your chest is going out instead of your abdomen then you're breathing wrong.