Unlike everyone else in the administration, Pence does not serve at Trump’s pleasure. Trump can demand that he do his bidding, but he can’t fire him. Because Pence has been a GOP soldier for so long, Trump can’t really damage him among the Republican rank and file. All this gives Pence a measure of freedom to protect himself from his boss.
More importantly, the vice president retains the esteem of congressional Republicans, who see him as their best friend in the administration and a reliable voice for conservative principles. Unlike Trump, he understands them, their political needs and the realities of legislating.
He also doesn’t throw them under the bus. Trump infuriated House Republicans who had voted for an unpopular Obamacare replacement bill by calling it “mean,” even after celebrating it with them at the White House. Pence wouldn’t do that. His ability to stay on the good side of both his boss and his party reflects his political savvy and talent for self-preservation.