At first glance, these look so similar.
You had better exercise.
It would be better to exercise.
However, the feeling you give when you say them is very different.
When you tell someone “You had better (…),” you are threatening them. That means you are telling them, “If you don’t do this, you will suffer! Something bad will happen! There will be negative consequences!” In other words, “You had better exercise. If you don’t, you will die soon because you are overweight, you have high blood pressure, and your heart is about to explode!”
In contrast, “It’d be better to” is more like “You should.” It expresses your opinion. “It’d be better to exercise than sit around and play video games all day. You should get outside and move your body more. You’d meet people, experience nature, and see more of the world.”
If you say, “You’d better not drive so fast,” the feeling is there are police everywhere with their radar guns out and ready. Perhaps it’s icy, and you’re worried your friend’s car is going to spin out of control. Your life is in danger.
In contrast, if you say “It’d be better to drive more slowly,” the situation isn’t so scary. You’re just giving advice. “Slow down and smell the flowers, look at the pretty scenery outside your window, use less gas, relax.”
If your boss tells you, “You’d better not come late,” he means “or else you’re out of here, fired, gone!” If he says, “It’d be better not to come late,” he’s giving friendly advice. “Please be on time. You can drink your coffee in the office. We’re counting on your participation and productivity.”
When choosing between them, think about your purpose. If you want to be scary, say “You’d better (not)…!” If you just want to share your thoughts, then “It’d be better (not) to…” is the better way to go.
Had better is followed by the simple form of the verb.
It’d be better is followed by the infinitive form of the verb.
(To make either of these negative, put “not” right after the word “better”)
For more practice, watch this video: