I absolutely love garlic, but recipes state many ways in which to prepare it: chopped, finely chopped, sliced, smashed etc. WHY? Is it to impart more flavour or texture ?
For garlic the main driver behind the preparation of the garlic clove is the strength of flavour required. The more you chop or crush the garlic, the more pungent it becomes. So if you only require a mild, infused flavour then you would smash, or bruise, the garlic clove. If you want a strong flavour then you would chop the clove very finely, or crush or mince it. Garlic can also burn very quickly so if you are adding it to a stir-fry or just wanting to flavour some oil before cooking other items then you will want to slice the garlic.
Another consideration is texture, mainly if the garlic is used raw or only lightly cooked - such as a salad dressing or a garlic butter. Here it isn't very nice to bite into nuggets of raw garlic so it is best to crush the garlic clove for these.
In older cloves of garlic there is a noticeable inner core. This can be slightly bitter so it is worth removing from the garlic clove before you use it.