ご質問ありがとうございます。
「区別がつく」は英語で「distinguish」と言います。文法の「〜にくい」は「hard to ~」なので、「区別がつきにくい」が「hard to distinguish」や「difficult to distinguish」となります。丁寧な表現です。
両方の意味とニュアンスが一緒なので、ご自由に使ってみてくださいね。
例文:
For Japanese people, it's difficult to distinguish the pronunciation of "R" and "L."
日本人はLとRの発音の区別がつきにくいんです。
ご参考になれば幸いです。
It's really difficult for Japanese people to tell the difference between L and R
「日本人はLとRの発音の区別がつきにくいんです」は英語で(違いが聞き取れない時) It's really difficult for Japanese people to tell the difference between L and R もしくは(発音する時)It's very difficult for Japanese people to make a distinction between L and R when speaking になると思います。
区別する- distinguish A from B, tell the difference between A and B
外国人は雨と飴の発音の区別がつきにくいです - It's very difficult for non native Japanese speakers to pronounce "rain" and "sweet" correctly もしくは It's really difficult for non native speakers of Japanese to tell the difference between "rain" and "sweet"