Difference between Singlet and Undershirt

What is the difference between Singlet and Undershirt?

Singlet as a noun is a vest, or a similar sleeveless item of clothing while Undershirt as a noun is an upper undergarment with no collar, and with short or no sleeves, worn next to the skin under a shirt; a singlet or (british) a vest

We hope you now know whether to use Singlet or Undershirt in your sentence.