There is no difference as far as I know - they are both the same, i.e. a loan from a bank / building soc / credit union, over an agreed term (usually 3 - 5 years for a car) with an agreed interest rate. In terms of collateralising, they will not re-possess the car if you default(unless you're leasing a car and default on the lease, that's a different matter), you will be pursued the same as if you default on a personal loan. You can have the loan with / without 'payment protection', this is effectively an insurance presium that will pay the loan for a period if you fall ill, become unemployed etc.
Shop around for the best deal - check out [broken link removed], it goves a list of current borrowing rates in Ireland. Credit Unions seem to be the best value, although they have their won ruukles with regards to savings / track record etc. Also check out if you can increase payments / lodge lump sums to pay off the loan quicker withiout charge, this may be useful if your situation changes (for example SSIA money, job bonus)