Answer:
One includes 3 as a solution, one excludes it.
Step-by-step explanation:
Think about the difference between the phrase "they were shorter than me" and the phrase "they were no taller than me." In the first one, we're implying that this other person can't be as tall as you; their height has to be less than yours. In the second, we're allowing for the posibility that this person's height matches yours. x < 3 describes that first kind of scenario, while x ≤ 3 describes the second.
