Dash seeks to do what Bitcoin failed to do, be the main digital transaction system. Dash's focus is getting to a very efficient blockchain that can handle millions of transactions per minute while using very little electricity.

Helium seeks to be a blockchain service that both acts as a currency and a way to manage data flow for companies that want blockchain services. Since it is decentralized, Helium can have as many clients as it has service nodes. So Helium can expand as fast as the market allows.

So Dash is money, buy groceries or PC parts online. Helium is more like Ethereum, serving business needs and B2B needs. Given how hot blockchain tech is now, I think they'll have clients lined up to get node service.