what's the difference between 异常 and 特别?

异常 = abnormal/ out of the ordinary usual practice
eg: someone who doesn't like coffee and never drinks it but one day you saw them drinking expresso
特别 = special
eg: can be used to describe something as special or especially.
she's a special person 她是一个很特别的人
this dress is especially pretty 这条裙子特别漂亮

1.when they use as adv., "异常“can be teanslated as "unusually","特别“as "extremely", they both can describe adj. for example, 异常开心，特别开心; but"特别‘’ can be translated as "especially" to address noun and phrase, e.g."特别是昨天“，”特别是在冬天"。

2.when they us as adj,"异常“can be teanslated as "unusual""abnormal","特别“as "special" in English.
他很特别: He is special.
他的表现很异常： His behavior is abnormal.

3."异常"can be used as noun， 这份报告出现异常，This report shows abnormality。

In Mandarin Chinese, 异常 (yì cháng) and 特别 (tè bié) are two words that can be translated to English as "unusual" or "special." However, there is a difference in the connotations of these two words.

异常 (yì cháng) is used to describe something that deviates from the norm, something that is not typical or normal. This word is often used to express a negative or abnormal situation, such as an "异常天气" (yì cháng tiān qì), which means "unusual weather."

特别 (tè bié) is used to describe something that is unique, exceptional, or distinct from others. This word is often used to express a positive or special situation, such as "特别有趣" (tè bié yǒu qù), which means "very interesting."

So, in summary, 异常 focuses on the abnormality of a situation, while 特别 focuses on the special or unique qualities of a situation.

异常 和 特别 都是说和平常不一样。
但是“异常”adv. 用来指同一事物与平时不同，与正常情况不同，被称为“异常”。
“特别”adv.和adj.指和一般不同的做法，不同的事物，强调与其他事物，其他做法比不同。
EG :
今天这个孩子异常兴奋。（他平时不这样兴奋，别人也不这样。）
今天这个孩子特别兴奋。（他非常兴奋，他比别人兴奋。）

特别的用处更广泛，指类似物品中的一些区别。异常是指情况更不同寻常、更加特殊的情况。

异常 (yì cháng) and 特别 (tè bié) are both adjectives in Chinese that describe something as being different or exceptional in some way, but they have slightly different connotations.

异常 often implies that something is abnormal or unexpected, and may have negative connotations, for example:
医生说他的身体状况异常。(The doctor said his physical condition is abnormal.)

特别 typically has a more positive connotation and emphasizes that something is special or unique, for example:
这场演唱会特别精彩。(This concert was especially wonderful.)

So, 异常 is more likely to be used to describe something that is unusual or deviates from what is normal, while 特别 is more likely to be used to describe something that is exceptional or stands out in a positive way.

In general, 异常 has a potential negative emotional colouring to it. It's usually used in circumstances where you believe the the thing you're describing is unusual in a bad way. 特别 is more neutural; you don't expect it to be neither positive or negative.

When used as adverbs, 异常 has a stronger exclamation level than 特别 (which is similar to 非常 in this circumstance). 异常 as an adverb is also used when you suspect that something (not right or you do not know) is going on, like 他今天异常兴奋（是不是听说了什么好消息？）。