It keeps capitalizing “must” and L in litercay, in the tag bar.

“Must” expresses unequivocal obligation: you gotta.

“Should” is more tentative: you oughta.

I should be more careful about my diet, but I must eat something right now or I’ll pass out.

It’s not about legality. It’s about the meaning of the words.

SHOULD is a suggestion. Typically it means it is beneficial for you to do something. MUST or SHALL are directives, imperatives. They carry the strength of a rule or law.

“Should” gives you a choice.
“Must” does not.

It is the same as the difference between Will and Shall. Should and Will leave the option to not do something, while Must and Shall do not.

“Must” and “should” are both modals that convey similar senses but at different degrees. “Must”, like “have to”, conveys obligation or requirement. “Should”, like “ought to”, conveys a suggestion or recommendation.

English has a lot of modals and some of them with only subtle differences between them. For example, “must not” is stronger than “don’t have to”. The latter relieves you of obligation; the former is simply a negative obligation.

Should and must can also be moral or practical or even physical perspectives, not necessarily legal perspectives or directives from others.

In all cases, “should” refers to something that ought to (or is expected to) be done or be the case, while “must” refers to some sort of necessity (which could be subjective or incorrect, depending on perspective).

Examples:

One should eat after swimming, not before.
One should be aware of and respect the riptide (or bear).
The cat should appear about now; he always does.
You should put the ice cream in your cart after doing the rest of your shopping, so it won’t melt.
That tree should stay up even in high winds.

One must eat something sometime in order to remain alive.
We must leave before the stormtroopers arrive.
What goes up must come down (except, say, light, or spaceships).

Possible common sources of confusion:

Should and must may begin to seem similar when reading or listening to people who misuse the words, or who abuse “must” to try to linguistically insist that their perspective or authority is correct. Legal documents, authoritarians, certain religious types, and others who overstate authority may tend to overuse “must” to sway the weak-minded.

You “must” do “your” homework.
The wife “must” obey the husband in “all” things.
The law “must” be observed in all cases.
“Everyone” “must” meet their “Maker” in the end.

Thanks all. Is there another consequential difference, especially if used with an auxialiary verb?