confused about ohms law- but let's try to keep this in laymans terms

im debating with a friend right now:

okay ohms law says something like more voltage = more current kinda set up which would mean more power, right?
so im thinking voltage is like pressure pusshing the current... which would = more power...
my friend says that current is based solely on resistence that it's pretty much the less resistance the more power...

this is the way he thinks...
bigger pipe more water flow.. smaller pipe less water flow

the way im thinking...
although it's a bigger pipe, in order for more water to flow you'll need more pressure pushing the water for it to be efficient...

any input?