Both are the same. Alkaline ionized water and hydrogen water generators have the same working principle or technology called electrolysis.
Both are the same and proven advantageous in their own way, and the combination of two is parallel. As pH of the water raises through electrolysis then hydrogen concentration also rises. Ultimate truth is that alkaline ionized water and Electrolytic hydrogen water both are the same. Through natural electrolysis, both generate the same amount of dissolve hydrogen up to 1300 ppb, which is the maximum safe amount of dissolved hydrogen for drinking as per JIS JAPAN standards.
The final outflow of water is called Alkaline Ionized Water or Electrolytic Hydrogen Water.