The cause of heart attack
is a narrow or blocked heart artery
, a balloon is positioned at the site of block and inflated under pressure. It dilates the blood vessel at that point - this is 'ballooning'.
It can collapse immediately after removing the balloon and the catheter. To prevent this, a stent
is put in that place.
Nowadays "stenting' is routinely done after ballooning... The words are used interchangeably - any one word means both. There is practically NO difference