The main differences between the Dolphin Explorer E50 and the E70 are their size, suction rate, drive system, full bin indicator, accessories, and warranty. The E70 is slightly bigger than the E50 and has a higher suction rating of 5000 GPH than the E50's 4000 GPH. Also, the E70 comes with a Dual Drive system, while the E50 features a single-drive motor. And for the warranty, the E70 comes with a more extended warranty of 3 years compared to the 2 years of the E50.  Another difference is that the E70 has a full bin indicator with five different levels for varying levels of debris, while the E50 has a standard full bin indicator. The accessories that come with each model may also differ.