Difference between unsweetened, sugar free and no added sugar

No carbs as much as possible.

Nothing to do with "sugar" per se as carbs all turn to sugar once ingested so it is carbs that are the T2's problem not just sugar.

Foods labelled no added sugar still contain sugar - eg fruit juice. In some cases the food may take the word sugar literally and so contain honey, etc. Which is ridiculous as that is sugar.
Sugar free is often misused, and may mean no added sugar although that is changing. It should mean no sugar at all, including no naturally occurring sugar.
Unsweetened, again can contain natural sugar.

But the key measure is carbs, in the USA net carbs (ie minus the fibre), in the UK the carb count does not include fibre. Our bodies convert carbs to sugars.

Sugar free is probably the safest bet purely from a diabetes perspective but it usually means full of artificial sweeteners and any other untold number of things. Or 100g of grain carbohydrate.

Neither - turn the package around and look for the full nutrition breakdown - any of those three options could be high in carbohydrate.
Something eight percent sugar would be a better option than no sugar and sixteen percent carbohydrate.

Hi, Yes, you only need to look at the back of the food packaging and find Total Carbs. If there is no packaging then Google what is typical Carbs for that food. It's not about Sugar but Total Carbs.