Yes, the primary difference between the USN MH-53E Sea Dragon and the USMC CH-53E is the enlarged fuel sponsons. The MH however does not utilize external fuel tanks like the CH does. It includes a more advanced avionics package and of course the specialized ASW electronics. The airforce also operates a series of MH-53J Pave Low for special operation missions. The 53J however is much more similar to the CH-53E then the MH-53E with the exception of the avionics platform.
Actually, the MH-53E has more powerful engines due to a different fuel control in addition to the large sponson fuel tanks. The 53J is not really similar to the MH or CH-53E as it is based of the 53D airframe. This means it has two engines (vice 3), no canted stab, and 6 rotor blades (vice 7). It does have stronger engines than the CH-53E...I believe its two of the engines the MH-53E uses (GE-419) instead of the GE-416/A's the CH-53E uses.