tell apart, distinguish

I tell the real one.

私は本物を見分けます

I tell the real one at the shop.

私は店で本物を見分けます

I tell the real one at the shop after listening to the expert.

私は店で専門家の説明を聞いて本物を見分けます

I tell the real one at the shop with my friend after listening to the expert.

私は店で専門家の説明を聞いて友達と本物を見分けます

I tell the real one from the fake at the shop with my friend after listening to the expert.

私は店で専門家の説明を聞いて友達と本物を偽物と見分けます