The differences between master limited partnerships with variable rate distributions and regular MLPs may be basic, but they are significant, and investors should know what they are. In this video, Fool.com contributor Aimee Duffy explains some of the characteristics of variable MLPs such as CVR Refining, Northern Tier Energy, and Rentech Nitrogen Partners, and why investors may or may not ever want to buy in.

Fool contributors Aimee Duffy and Tyler Crowe have no position in any stocks mentioned. Nor does The Motley Fool. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.