I believe Newton was much more important than Einstein in the history of Science. Essentially he laid the starting point for "Modern" Physics/Mathematics and everybody since then has been following on from there.

For me there are only three Scientists who could be called as truly "tectonic inducing" in the history of Modern Science. In order of ranking;

1) Isaac Newton.

2) James Clerk Maxwell.

3) Albert Einstein.

I would say Newton provided a similarly important discontinuous leap in our understanding of nature.

I want to be careful though. As some sibling comments mention, these discoveries of these great people were indeed "in the air" of their time. They will have happened. But it would have taken many more great scientists and more time.

For instance, I believe there are incredibly deep insights today derived from the mixture of quantum mechanics and information science. More deep insights are imminent and inevitable. But there is hardly one towering figure to do them all in one sweeping motion the way Einstein or Newton or Euclid did (to name a few easy examples).

Newton was more important I think. He basically invented physics as we know it. He didn't have the 200 years or so of work in the field that Einstein had to build on. He was effectively starting from scratch. He's the point at which the modern world starts, when humanity started to understand the world around them instead of letting themselves be subjects of superstition.