这些 = these 这 + number + measure word = these [number] e.g. 这三个 = these three (Just remember to use 两 instead of 二 for "two" and that 一 can be omitted in "one") 几 can be used to ask "how many" or to answer how many (as the word order doesn't change), usually referring to a small number (often a single character), so "(a) few" or "several" are common translations, so if you put this in place of "number" in the structure above (这几个) then you are saying something along the lines of "these few" or "these several". With 些 there is no hint to the quantity.

In this sentence, the meaning of几个 is almost the same of 些。 You can also say, 这些地方都差不多。 But if you want to ask "how many", you should ask"几个" but "些"。For example, you want to ask somebody 你去过几个地方? You shouldn't say "你去过些地方?" In other case, someone can ask you "你去过哪些地方"? it focus on "which places" have you ever been, not only "how many". I hope this helps.