There also seems to be a vague distinction between, say, C-3PO and R2, who are both always referred to as male, and then the Trade Federation droids like this one, who seem to mostly, but not always, lack sentience, and are fairly wholly reliant on an external "brain", if you will, a la The Phantom Menace, or indeed the Omega in Edge of Tomorrow. So... Yeah.
There also seems to be a vague distinction between, say, C-3PO and R2, who are both always referred to as male, and then the Trade Federation droids like this one, who seem to mostly, but not always, lack sentience, and are fairly wholly reliant on an external "brain", if you will, a la The Phantom Menace, or indeed the Omega in Edge of Tomorrow. So... Yeah.