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A razor blade is sharper. An exacto knife is thicker and stronger. That said.... an exacto knife can handle more pressure without breaking. More pressure means better cutting. So I guess I'm saying that if your scraping then a razor is good. If your cutting the exacto will actuall cut better because you can put more pressure at the blade.

Sharpest between the two would be the razor blade. The strongest would be the typical Ex-acto blade.

Sharper than these would be a surgeons scalpel. Next up would be the lab techs microtome (cuts slivers for microscope specimens).

They are both razor blades. Exacto is easier to cut with. you change the blade when it gets dull. What r u cutting?

Razor blade. A laser is sharper...but you can't have one.