比 (bǐ) — comparing two things
To say 'A is taller than B' in Mandarin, use 比. Pattern: A 比 B + adjective. 我比你高。 = I'm taller than you. (Literally: I-compared-to-you-tall.) The crucial difference from English: NO 是, NO 很. The bare adjective sits at the end. 很 would actually be wrong — under 比, the adjective stops needing its usual filler. The flip side traps: 'not taller' is NOT 不比 + adj. The everyday negative comparison uses 没有: 我没有你高。 = I'm not as tall as you. And 'just as X as' uses 跟 ... 一样: 我跟你一样高。 = I'm as tall as you.
The basic pattern: A 比 B + adj
A 比 B + adjective — that's the whole frame. 我比你高。 = I'm taller than you. 她比我大。 = She's older (lit. 'bigger') than me. 这本书比那本书贵。 = This book is more expensive than that one. 中文比英文难。 = Chinese is harder than English. Notice what's NOT there: no 是 linking the adjective, no 很 softening it, no 更 ('more'). The comparison is built into 比 itself. 我很比你高 is a beginner mistake — drop the 很.
Adding a degree: 一点, 多了, 很多
To say 'a little' or 'a lot' more, attach the degree AFTER the adjective. 我比你高一点。 = I'm a little taller than you. 她比我大三岁。 = She's three years older than me. 中文比英文难多了。 = Chinese is much harder than English. 这本书比那本贵很多。 = This book is much more expensive. The numerical version (大三岁, 高十厘米) lets you give the exact gap, which Mandarin does naturally without 'by' the way English needs.
Negation: 没有, NOT 不比
The single biggest trap. To say 'A is not taller than B', you do NOT say A 不比 B 高 in everyday Chinese. The natural pattern is A 没有 B + adj = 'A doesn't reach B in this quality'. 我没有你高。 = I'm not as tall as you. 这本书没有那本贵。 = This book isn't as expensive as that one. 他没有我大。 = He's not as old as me. (不比 does exist but has a special contradicting flavor — 'actually NOT taller, despite what you said' — and is rare in beginner speech. Stick to 没有.) Note the structure echoes the lesson 9 没有 = 'don't have / there isn't', extended here to comparisons.
Saying 'just as X as': 跟 ... 一样
For equality — 'A is the same X as B' — use A 跟 B 一样 + adj. 我跟你一样高。 = I'm just as tall as you. 这本书跟那本一样贵。 = This book is just as expensive as that one. 跟 (or 和 from lesson 5) introduces the partner; 一样 yíyàng = 'the same'; the adjective sits at the very end. To say 'just the same' with no adjective, drop it: 我跟你一样。 = I'm the same as you. Negate with 不: 我跟你不一样。 = I'm not the same as you.
Comparison questions
Two common patterns. (1) A 比 B 怎么样? = How is A compared to B? 中文比英文怎么样? = How is Chinese compared to English? (2) A 跟 B 一样吗? = Is A the same as B? 这本书跟那本一样贵吗? Or use the V-not-V flavor: A 跟 B 一样不一样? Bigger picture: comparison is one of those grammar nodes where Mandarin clusters several specialized patterns instead of one all-purpose word like English 'than' / 'as'.
