Can anyone tell me the difference between a garnishment on my wages and a levy?

They are essentially used synomonous.

Wage Garnishment is a levy that the IRS has the right to issue to an employer of a taxpayer who owes the IRS money. The IRS must give proper notice to a taxpayer before it can actually issue the levy. A proper notice constitutes several form letters ending with a letter with a Final Notice of Levy attached. Once the notice has been sent to the taxpayer, the IRS can issue a garnishment after 30 days from the date of the letter.

So essentially the levy is used to garnish your wages.

Off the top of my head:

Garnishment: An ongoing deduction from your paycheck until the debt is satisfied. If they take $200 from each paycheck they will take $200 from every paycheck in future until the debt is paid.

Levy: A seizure of bank funds in a bank account on a specific day. If there is $412.19 in the bank account on the day the IRS looks, they take $412.19.