A Regular Plan is a version of a mutual fund purchased through an intermediary — a distributor, bank relationship manager, or financial advisor — who earns an ongoing commission for selling and servicing your investment. This commission is built into the fund's expense ratio, so regular plans always cost slightly more per year than the identical fund's direct plan.
In exchange for the higher cost, you typically get guidance on fund selection, help with paperwork, and someone to call if you have questions or want to make changes. Whether a regular plan is worth the extra cost depends entirely on how much you value that hand-holding — for investors who prefer a do-it-yourself approach, a direct plan of the same fund usually makes more financial sense over the long run.