Does 差不多 (chàbùduō) imply "slightly less than" when comparing quantities?

Question

差 implies a kind of deficiency, so I expect

A比B差不多

to mean A is slightly "worse" than B in some way. For example, I would expect

我比你差不多高

to imply I am slightly shorter than you. I'm not sure if this is correct, as 差不多 is also used to mean "about".

Question: Does 差不多 imply "slightly less than" when comparing quantities?

I could imagine a conversation along these lines (I made this up):

A：你说那本书是50块，可是就是52块，你说错了。
B：哎哟，差不多吧。

where A is grumpy that the book was 52 yuan, when B previously told A that it was 50 yuan, but B says it's 差不多 (much the same). In this context, it seems like 差不多 means "about" and not "almost". Here 52 is greater than 50, so this raises some doubt.

Answer 1

差 = 相差 (difference) ;差距 (gap)

不多 = not much

差不多 :

(adj) not much difference/ not much gap between

(adv): almost / about

Example of 差不多 as adjective:

味道差不多 (not much difference in taste) - could be slightly better or slightly worse

價格差不多 (not much difference in price) - could be slightly higher or slightly lower

Example of 差不多 as adverb:

差不多到了 means "we're almost there" (not quite there yet, but close to)

差不多死了 means "almost died" or "about to die" ( not dead yet but will be soon)

When A ask B how much is the book, and B said: "差不多50块", it mean "it is almost 50 yuan" (= not quite 50 yuan)

When A found out the actual price is 52 yuan, he has every right to accuse B of lying.

And B's excuse: "52块, 50块 差不多吧?" (52 yuan and 50 yuan is not much a difference right?) is using 差不多 in a different way.

Does 差不多 (chàbùduō) imply “slightly less than” when comparing quantities?

When 差不多 is used as an adverb (is almost) + quantities, it dose imply “slightly less than”, But when 差不多 is used as an adjective (not much difference), then it only mean the objects are similar in some form of comparison.

A 比 B 差不多

The correct form:

A 跟 B 差不多 = not much difference between A and B

A 比 B 差不了多少 = Compare to B, A is not much worse

A 比 B 差不多 is not grammatical

Answer 2

The most common phrasing is A和B差不多. 差不多，as a whole, means not much difference.

You can say 你的身高和我差不多 or 我们俩个差不多一样高.

If you want to use 比， you can say 和我比你还差得远，你和我比还差得远 etc.

It's worth to note 你比我差不多 doesn't work quite well because 差不多 is almost a set phrase to mean not much difference(which is different from what you expect it to mean).