The way I understand it 彼【かれ】 means 'that person over there' and あちら also means 'that person over there'
彼 is strictly male and means "he" rather than "that person over there". Worth noting is that the he/she pronouns aren't as commonly used in Japanese as in English and 彼 can also mean "boyfriend". あちら is rather polite/stuffy for "that person (over there)" but it can also mean "over there" or "overseas".
あちらがお父様ですか？ Is that (person standing over there) your father?
The most common expression for "that person" is however あの人, though it might be a little bit too casual depending on the context. A very impolite form that's sure to offend, on the other hand, is あいつ (or あのやつ).
It depends on the situation but in this case 彼 is 'he', あちら is 'that person'. 彼 is just a little bit more friendly, あちら is formal.