cravingcake, re: the epidural, I had one and honestly, it was nothing. Certainly less than nothing compared to the pain I was in from back labour. You really don't feel much. The anaesthesiologist numbs the space between the L1/L2 spinous processes in your back (the bumps on your spine) with a local anaesthetic, and that is seriously the worst of it. He or she will wait a minute to make sure the local has taken effect, and will then insert a needle cannula. It feels like being tapped with the eraser end of a pencil. You may feel a tiny pop as the needle cannula goes in, because it has the get through quite a thick ligament between the spinous processes. After that, the anaesthesiologist feeds a tiny flexible line through the cannula into the space around the bottom strands of the spinal cord, and injects anaesthetic. If you're in hellfire agony, it's the most blissful feeling in the world... like cool water running down your back. Indescribable. If you're not in any pain, you will still feel a cool sensation in your back. Then you'll lie down, and in a bit you won't be able to move or feel your legs, and they'll keep testing the effectiveness of the anaesthetic by placing ice bags on your abdomen and asking if you feel anything. At least that's the protocol here.
As far as the difference between a spinal and an epidural anaesthetic are, the mechanics of administration are the same. An epidural anaesthetic is usually hooked up to a continuous infusion machine, because you don't know (usually) how much longer a patient will be in labour, and as only a tiny amount is infused per minute, just enough to keep it effective, it can also be discontinued as needed, or dialled down when a woman is ready to push.
A spinal anaesthetic is given as a single dose, and not attached to a continuous infusion pump, and is thus used for scheduled ops when it's normally quite predictable how long the op will last. The dose is calculated to last as long as needed, but can be topped up at need.
Does that help at all? Really, the actual injection is nothing. If you've had a booster jab in your arm, I'd almost say that burns worse. The back just isn't that sensitive.