A bit late, but;
As far as overhead (aerial) conductors go - who knows?
There are copper conductors (hard-drawn bare copper conductor, HDBCC), various kinds of aluminium alloy of which AAAC 1120 is the most common these days, and various mixes of aluminium with steel strands (for tensile strength.)
Copper isn't used much these days. Aluminium conductor is cheaper and lighter (which reduces the demands on the overhead tower structures) so it is used for nearly all new overhead lines.
As far as solid insulation goes, for cables you could bury in the ground;
Up to the 1980's or so it was common to use paper-lead insulated cables. That is, layers upon layers of brown kraft paper, wound up to the required thickness, and impregnated with oil, wax, or resin di-electric; then, over-sheathed with lead sheeting to provide waterproofing and stop the oil/wax/resin from leaking out.
In Australia paper-lead cables were called 'PLA' or 'PLY' or 'PILC' (paper insulated, lead covered). There is also the acronym 'PLYSWAPVC' standing for 'paper lead y(?), steel wire armoured, PVC sheathed.'
Starting in approx the 1990's, it is more common for HV cables to have solid plastic insulation. The particular plastic in question is called 'XLPE', cross-linked polyethylene. This stuff had some early failures caused by a susceptibility to water damage, but that's mostly fixed now.
As far as 'non-solid' insulation goes - there is one kind of cable where the insulation is liquid oil. The "cable" looks more like a pressurized water pipeline than a cable. There's another kind of "cable" where the insulation is SF6 Nitrogen gas.
Here is an entertaining story about the failure of an oil-filled cable in Los Angeles. And another story about the failure of a gas-filled cable in Auckland.
For power system analysis purposes, where you often don't know the age of the cable, the safest assumption is that it's all paper-lead (which has the lowest current-carrying capacity.)
XLPE would be common for newer cables. Due to the amount of special care and handling for oil-filled and gas-filled cables, I think they were only ever used for short runs when very high capacity is required, i.e. in dense city centres. These days, for a new installation, I think you would install XLPE instead.
Best Answer
From The obvious place