Whats the point in studying a HNC (Higher national certificate)?

Im currently at college studying I.T. practitioners course level 3 which is the A-level standard. Im on my first year of the two years i need to do to finish this course. But I would like to go onto getting a degree after finishing my a-level I.T and am looking into HNC because my college offers them and it is available for me to do after this course. But what is the differences between doing a HNC or going straight onto a degree.