The difference is the amount of concentrated perfume oil in it. Read this post and have a full understanding of them.
Perfume sillage is the word for measuring a perfume projection rate around a person. Read this post as we talk into details of sillage.
Fake tester perfumes are flooding the market, almost 80% of online vendors selling testers are fakes but fear not ! Once you read through this post, you will never be cheated again !