What kind of grass does your neighbor have?

What kind of alternatives are you thinking? Some people plant ground covers. Some plant meadow wildflowers. I'm planting native prairie grasses, but mowing so it looks like a lawn but a different shade of green and using less water.

bp I didn't know you were doing that. Interesting. What grasses are you planting and how often do you plan to mow.

I'm growing mostly western and streambank wheatgrass, with a little sheep fescue and blue grama mixed in. I'll mow as often as needed to keep it at the highest setting of my mower deck.

I've also got one non-native in the mix--strawberry clover. It's similar to dutch white clover, but better adapted to alkaline soil.

I'm not sure what type of grass my neighbor has, it's just the regular old lawn grass that most people have I guess.

Where are you located? That would help to narrow it down.

Where I live, they would both "creep" into each other IMHO.