Hello everyone,
I wanted to know if anyone could explain to me the specifics for when to use either 「ただ」or 「だけ」or both. I know their meanings are similar (only, simply), but a friend told me that 「ただ」is used for hypotheticals and 「だけ」is used for solid, tangible things.
These are two words that unfortunately don’t have super good English translations 
. The main difference is that だけ focuses on a group of things, where one of those things is being removed/highlighted. ただ on the other hand translates a bit closer to ‘as it is’ (with focus on not adding or removing anything).
Maybe simpler-
ただ = (A) is just (A), however…
This is similar to the phrase ‘that said’ in English, where people simply acknowledge their previous statement before adding more info. For example “I love apples… that said, if it’s rotten, of course I won’t eat it”. So ただ should only really be used when you want to acknowledge a statement as being complete by itself, before adding more info.
だけ = From among (A), (B), and (C)… (A)
This is much closer to ‘only’ in English, but has a finer nuance than ‘only’. だけ cannot be used in cases where there is only one choice to begin with, there must be several.
A couple of examples (as they came to my mind, and i’m not that 上手 yet) just to remark Asher’s words:
ただの人です → it’s just a person (someone, generic).
果物の中で桃だけが好きだ → among fruit, i like peaches only. (only peaches, i dislike everything else)
Jisho lists for ただ ordinary; common; usual, which I find useful to remember. Also only; merely; just; simply, which is kiiiinda similar? Like, nothing special, only the usual, sort of?
Another example, please someone correct me if I’m wrong here:
ただの友達です。Just an ordinary friend (not a very close friend)
友達だけです。“Just friends” (not dating or otherwise related)