Student or Learner
Tom and Fred are twins. I say It isn't easy to tell Tom and Fred apart. Is this one correct too or not? I can't tell apart Tom and Fred. I mean Tom and Fred after apart.
The adverb goes after the verb's object, like this, tell them apart. Unless, of course, the verb phrase functions as an infinitive; e.g., They are a lot harder to tell apart.
All the best.