Mike clearly doesn't like Walt. He's upset that Walt was unwilling to just 'know his place', cook meth, and make as much money as he wanted.
Is it ever explained why Mike doesn't feel the same way about Gus? Gus and Walt share many of the same personality traits and seem to be nearly the same in how they handle the meth business. Gus isn't content with the money he was making and is willing to kick-off an international drug war, including personally poisoning countless cartel members. All to increase his profits/settle old scores. And Mike seems happy to stand by his side.
What's different between Gus's grab for power compared to Walt's?