Pay Per Click (PPC): PPC also known as EPC – Earning Per Click, you can understand PPC by words pay per click. it simply means that you get paid each time a visitor clicks on the ad or the sponsored link in your site. It is most fastest and easiest to way to earn money but this is short term deal. compare to long term result webmaster gain is probably very small.
Pay Per Sale (PPS) : When you promote PPS advertising or offers in your website, you generally earn more dollar for each individual sale, but they usually have a lower conversion rate than Pay Per Lead offers. The conversion rate is the proportion of converting site visitors into paying customers. PPS typically require the usage of a credit card. These kind offers are best for those webmaster's who have highly qualified traffic.
Pay Per Lead (PPL) : A Pay Per Lead offer is an offer where webmaster get paid each time a user makes a defined action. This is also known as Cost Per Action (CPA) as advertiser language. For example, you can get paid each time a user signs up for free or premium offer's.
After PPC this is 2nd fastest way to earn money faster compared to PPS. In this offer both sides advertiser and publisher have risk. if you are getting very high free member signups but no paid members then Risk goes to sponsor side. but if you have high Quality traffic which generates more paid members then you are in loss because lead amount is very less compare to sale amount. Example : Mostly PPL is $2.5 and PPS is $40. If the free leads you’re getting paid good money for aren’t converting to paid members, well, enjoy the Pay Per Lead opportunity.
Revshare (RS): It Means that you will always get a percentage of what your user spends in sponsor's website. This is lifetime offer's which never expires. This offer have highest risk among all offer's to webmaster and for sponsor lowest risk. this is simple partnership between sponsor and webmaster on referred user. For long Term these offer's have highest earning opportunity and if your goal is long term then go for it.