Based in the dictionary, 长短 = length and 长度 = length. What is the usage or difference between the two words?
Both 长短 and 长度 mean 'length'
长短 is mostly used colloquially; 长度 is more common in both literary and colloquial form
When in smaller scale, the two terms are interchangeable.
For example: 剑的长短通常是70-110厘米 = 剑的长度通常是70-110厘米 (The length of a sword is usually 70-110 cm)
When something can be short or long, using 长短 should be safe, e.g. 路线的长短不一 (the length of routes vary)
but using 长度 is the safest: 路线的长短不一 = 路线的长度不一*
When in larger scale, we only use 长度
For example: 泰坦尼克号的长度是269米 (length of Titanic is 269 m)
We don't say 泰坦尼克号的长短是269米
ships like Titanic can never be described as short
长短 can also be a shortened form of '长处短处' (strengths and weaknesses); 说人长短 means "criticize someone"