1. Giraffes are much taller than lions and elephants.

(Does this sentence mean that giraffes are much taller than the height of lions plus the height of elephants?)

2. Giraffes are much taller than lions or elephants.

(I think 'or' is much better. What is the difference between Sentence 1 and Sentence 2?)

1 could be taken that way, I guess! One way to clear it up would be to write, "Giraffes are much taller than either lions or elephants."

2 is better.

Thank you.

(Does Sentence 1 sometimes mean Sentence 2? A little confusing....)

1. Giraffes are much taller than lions and elephants.

2. Giraffes are much taller than lions or elephants.

They would be commonly taken to mean about the same thing, but if you take the word "and" to be like a plus sign (+), then the meaning changes.

I'd stick with the "or" conjunction.

He is the tallest boy in the class (comparative)

1. The sentence "Giraffes are much taller than lions and elephants" means that giraffes are taller than both lions and elephants individually, not their combined height. It implies that giraffes are taller than both lions and elephants separately, but it does not specify whether giraffes are taller than the combined height of lions and elephants.

To understand this sentence, you need to compare the height of giraffes with the height of lions and elephants separately.

2. The sentence "Giraffes are much taller than lions or elephants" uses the word "or" instead of "and". The difference between Sentence 1 and Sentence 2 lies in the conjunction used.

While Sentence 1 implies that giraffes are taller than both lions and elephants individually, Sentence 2 implies that giraffes are taller than either lions or elephants. In other words, giraffes are taller than the tallest individual of either the lions or the elephants. Sentence 2 does not require giraffes to be taller than both the lions and the elephants.

Overall, the difference lies in the comparison being made. Sentence 1 compares giraffes to both the lions and the elephants, while Sentence 2 compares giraffes to either the lions or the elephants.