この間 means "the other day," and 最近 means "lately, " ”recently," or "these days." 例） この間 ねぇ!あの子の靴（見て）!この間私が話してたものだわ! Hey! Look at her shoes! They're the ones that I was telling you about the other day! 最近 最近カナとコウタはいつも一緒にいるね。あの2人付き合ってるのかな? Lately Kana is with Kouta all the time. Do you think they're seeing each other? hope it helps! :]

この前→just before 最近→these days