How long does it take on average, to heat a water tank on gas vs electricity. Which is quicker and cheaper?

I have both electric and gas heating for my boiler. In my previous home i had electricity so it was very quick 20 min and the water was hot.........i turned on the gas heating in the new property and found that after 20 min the water was roughly the same temperature..............may be 3-5 degree warmer.....