Zero conditional for general cause-effect, first conditional for a likely future condition, and second conditional for a hypothetical stance with would, including the common If I were you pattern.

First conditional for general truth, zero conditional for future plans, and second conditional for past events, which is why were points to a completed action in time.

Zero conditional for polite advice, first conditional for habits, and second conditional for scientific facts, which makes melts a hypothetical outcome rather than a rule.

Second conditional for likely future events, zero conditional for hypothetical advice, and first conditional for general truths, because will marks timeless statements in standard grammar.

All three are first conditional variants, and differences come mainly from vocabulary choice, so teachers can treat them as one pattern for exams and reduce grammar categories.