hey Tam

this is just from my head...so it may not be completely correct

but

a spinal is an injection of 'drugs' into the epidural space and is alot more effective, providing a denser and more comprehensive block

an epidural involves the placement of a catheter into the epidural space and then the injection of 'drugs', the block takes longer to be effective and is not always comprehensive (such as patchy or incomplete blocks)

I had a spinal with my first labor, after 2 ineffective epidurals and it worked very well very quickly. Did not personally (as the recipient) notice much difference in the procedure

hope this helps
x