According to Goku, Blue can't be used for long periods of time because it saps stamina quickly, but Vegeta found a workaround by using God so that he could maintain Blue's power.
According to Vegeta, Goku found a way to maintain Blue's full power constantly.
They seem like the same damn thing except Vegeta needs Super Saiyan God to circumvent the stamina drop. Both are stated to keep Blue in tip top shape. Complete Blue being stronger would be great, but nobody ever mentions it being another form/semi-form on top of Blue like they do with Blue Evolved against JIren. It's just 100% of Blue's power, not 250% or something.
yrus