With the PTC, you earn by joining a site and then clicking on websites. They generally pay you 1-2 cents for clicking on the site and waiting a certain amount of time.
GPT are sites you also join that you go to sites and sign up for free, do surveys, etc. and you can earn money that way too.
Hope this helped.
Have a great day!
[PtcBox] -new sites- same owner with matrixmails

[neobux]
[clixsence]

[linkgrand]

[clicksia]
[wordlinx]

[twickerz]

[incentria]
[buxp]

[matrixmails]

[jillsclickcorner]

[clicks4cents]

[scarlet clicks]

[velvetclix]

[myfreeshares]

[cashcamel.net]

[donkeymails]

[linkbuck]

[buxmatrix]

[youcubez]

[hits4pay]