とき is a conjunction meaning “when,” so
both means “when you go home, please ring me.”
The grammar difference is
うちにかえるときでんわしてね has かえる (non-past plain verb) before とき and
うちにかえったときでんわしてね has かえった (past plain verb) before とき.
When a “non-past plain” verb is used before とき, that means the action of that verb has not been completed when the action of the verb after とき happens. In short, うちにかえるときでんわしてね means “Please ring me when you are coming home” or “Please ring me when you are on the way home.” So it is likely someone at home is asking her to ring.
On the other hand, when a “past plain” verb is used before とき, the action of that verb has to be completed when the second action happens. So うちにかえったときでんわしてね means “When you are back home, please ring me” or “After you get home, please ring me.” So it is likely someone who is not home is asking her to ring.
I bought it when I was going to Japan.
I bought it when I went to Japan. (Most likely “when I was still in Japan.”)
When I was getting off the train, I saw Hanako (on the train).
When I got off the train, I saw Hanako (in a station).
For more beginners’ study material, please visit JLPT N5 Grammar and JLPT N5 Kanji pages.
One thought on “かえるときでんわしてね vs かえったときでんわしてね”
Differences among ～と, ～とき and ～たら | EasyJapaneseE1 July 2020 at 10:02 pm
[…] By the way, as shown above, the word とき can be used with both a past non-past verb (like the sentences b and e) and a past verb (like c and g) and there is a small but distinct difference between the two, so if you are interested in that, please read this post. […]