In context of perfumes, regular retail pack is the complete packaged perfume made for showcase. You will get the sealed bottle in a fancy box packaging. Bottle is always sealed pack but outer box may or may not be laminated, it varies from product to product.
Testers are the same product, same sealed pack bottle but since they are for purpose of testing ( try before purchasing by a consumer in showroom) , outer box is not made attractive but a ordinary brown / white box. Some products may have ordinary cap also, but off course every product related details are printed on box like a retails pack.
Now you can understand that tester and regular retail pack are two forms of same product but having different outer box. Testers are always economical and preferred if you want for personal use. If you are purchasing for gift purpose, definitely you will prefer a attractive packaging of regular retail pack.