Dear Student ,
The difference between the alkaline cell and the NiMH cell is given below :
1. Alkaline cells are not rechargeable but the NiMH cells re rechargeable .
2. Alkaline cells have higher starting voltage and as the load increases the voltage and capacity both decreases .But the NiMH cells are rechargeable so when they have the voltage drop they can be charged again .
3. Alkaline cells are long lasting than a same size rechargeable battery under same conditions .
4. The discharge slope of alkaline cells depend on the current drain , higher the current drain faster the battery discharges .But the NiMH cells discharging slope is straight line .
5. Alkaline cells are of single use as thy are not rechargeable but the NiMH cells are rechargeable so they can be used multiple times .
Regards