Which one is better?
In terms of macro, I think “10gram of carbs inclusive 1~2 grams of sugar” is better, but then I heard that sugar is a no-no. So I am confused.
carb in the context here can mean both net and total.(I know the difference is without or with fiber, and I know that most people are using net carb, but I also heard that some people use total carb to count instead.)
Carbs are carbs… 20 is worse than 10 or 12 unless you are absurdly allergic to “sugar” (you are not)… now get on with it! 
I don’t think you know what limit you have for carb eating and staying in ketosis - 10/20/30/50 etc. Nor does 1 or 2g really matter since that is way less that the margin of error for portion size, variations in specific item of food you have in your hands etc. All labeling is indicative so anyone who thinks they have correctly calculated the ACTUAL grams of carbs they have consumed is deluding themselves… 
Aim for 20g net of any carbs and see if it works.
Erm… yeah. I only use the common number. <_< In fact, I didn’t even test yet, as I didn’t intend to spend money on those keto test strips.
The reason why I asked question like this is … well, lots of people seem to treat sugar as the archenemy, and it makes me wonder if one gram of sugar is worse than 10gram of carbs, or even more. <_<
Something slightly out-of-topic: it seems like a lot of people feel that Adam Peanut Butter is much better than Peter Pan Peanut Butter, even when both of them have the same amount of carbs, just that Peter Pan has sugar in while Adam has no.
Well, I guess it depends on how your own body reacts with insulin and cravings. Maybe 1-2 grams of sugar is enough to set off cravings. Then yes, that would be bad. 1-2 grams of lettuce will probably not start cravings.
I’m curious how the two peanut butter have the same carbs if one has sugar. I can tell you the Peter Pan definitely is very sweet. I haven’t tried the other brand.
Edith
Well, yeah. They have the same amount of carbs.
And the serving size is the same also.
But that is just what comes to my mind suddenly after I posted this thread.
The difference between sugar and other carbohydrates is that most carbs are made up of long chains of glucose molecules, which is the sugar we are talking about when we speak of “blood sugar.” But sugar in the context of food generally means table sugar, sucrose, which is formed from a glucose molecule bonded to a fructose molecule. (Fructose is found in fruits, hence its other name, “fruit sugar.”)
Glucose is handled by the body with no problem. Carbohydrates break the chains into individual glucose molecues, they enter the bloodstream and are carried to muscles and fat. The insulin response to all that glucose signals the muscles to burn glucose for energy, and fat cells to store it as tryglycerides. So far so good (except for that spare tire).
Fructose, on the other hand, can be metabolized only in the liver, where it follows the same pathway as the ethyl alcohol in your Scotch. Because it’s metabolized by the same pathway, it causes the same problems in the liver, inflammation, de novo lipogenesis leading to fatty liver disease, elevated liver enzymes, that sort of thing. Fructose also acts upon the nucleus accumbens, the brain’s reward center, the same way alcohol and cocaine do, stimulating cravings and down-regulating dopamine receptors. (It doesn’t destroy brain cells the way alcohol does, however.) About the same percentage of the population gets addicted to sugar as gets addicted to alcohol, although I don’t believe they are all the same people.
So that’s why sugar is an especially bad carbohydrate to eat, especially if you are on a ketogenic diet for the metabolic benefits, or if you are a sugar addict.
