Ryobi One+ RB18L40

When comparing the Ryobi One+ RB18L40 and the Ryobi One+ RB18L50 power tool batteries, the key difference lies in their battery capacity. The RB18L50 boasts a higher capacity of 5 Ah compared to the RB18L40's 3 Ah, providing longer usage time between charges. However, this increased capacity also results in a slightly heavier weight for the RB18L50. Both batteries share the same 18V battery voltage and come with a single battery pack for convenience. Ultimately, the choice between the two would depend on the user's preference for longer usage time versus a lighter battery weight.