Usually by the colors. Neutral is white, ground is green or bare and hot is black or sometimes colored like a red, if you are in North America. If you have a voltage detector you can use that to find the hot also.

The two insulated wires are not colored. Both are insulated in a clear plastic. Both look the same. The thirs wire is not insulated and looks thiner.

Where are you located and what are you working on?

Located in Florida. Trying to install a ceiling light fixture.

You must be talking about the wires coming out of the fixture, right? If so it doesn't matter much you connect to your ceiling box hot and neutral. The box should have white, black and green or bare.

It does matter how a fixture using a two wire cord that is not color coded.

One wire will have a rib or notches in the insulation, or otherwise "identified", the other will be smooth or have no markings, The identified conductor will be the white neutral.

Like tk mentions, it has a ridges douw the side of the wire very hard to see, almost have to feel for it, this makes sure the shell(outer part of the socket is NOT Hot.
A multimeter could determine as well, the center pin needs to be the hot(more protected from accidental contact).

Both insulated wires look the same but noticed on the clear insulation of one of the wires there are some very small faint black markings, very hard to see. Do you think this is the neutral wire? Also the third wire from the fixture is not insulated. It looks more like a rope wire. I assume this is the ground wire?

The black marks you see identify it as the neutral, which will connect to the screw shell of a lampholder.

Yes, the bare wire is the equipment ground.

Yes both clear wires will LOOK the same, did you FEEL for ridges or ohm it out? All else use TK's advice.