While your abilities are still below lifting 160kg on any given weight, and you are performing the major powerlifting movements (squats, deadlifts, bench press, overhead press) then there isn't a major advantage one over the other.
However, there are reasons why you would opt for Olympic plates:
- Standard bars are roughly 1" diameter, but there is enough variance that there is no guarantee that plates from one manufacturer will fit on a bar from another manufacturer.
- Olympic plates have tolerances that must be met: the hole must be 50mm, the largest disk is 450mm on the outside dimension. This ensures you can mix and match your plates and know you can use it on your Olympic bar.
- Olympic bars also have tolerances that must be met: 20kg bar, sleeves must fit plates with 50mm holes.
- The sleeves on Olympic bars spin allowing you to do cleans and snatches with minimal stress on your elbows.
- Olympic bars can use either less expensive metal plates, or bumper plates which are designed to be dropped without being damaged or damaging the bar. Bumpers are useful for Olympic lifts like cleans and snatches, but don't do a whole lot for powerlifting lifts.
- Standard bars cannot handle much more than 160kg before they permanently bend.
- Olympic bars can be made to handle weights in excess of 500kg.
There are more subtle differences between Olympic style bars that are outside the scope of your question which deal with its suitability for one barbell sport over another.
When you are starting out, it makes sense to use the cheapest weights you can get your hands on. However, if your focus is on strength, there will come a time when you outgrow what the standard set will be able to do for you. At that time you will be forced to upgrade.