there are some difference between this two character in usage: 打仗(√) 打战(×) at war, fight , fight a battle 战争(√) 仗争(×) war (battle, fight) when the character 仗(noun) means 'war'(there'er other meanings of 仗) , normally as the word '打仗'(verb): 那时两国正在打仗 At the moment the two countries were at war. 打胜仗 win a battle (仗 can be a fight ,a battle) and it doesn't particularly indicate a location,time,or the scale of war. 战(noun & verb ) 战争(noun): war 战胜(verb) :defeat,win ,beat, overcome when you indicate a certain war like WW II(二战) Civil War(南北战争)，you must use the character 战. and in Chinese, 战 usually be combined to the items which associated with war, like 战机(warplane) 战马(steed) 战场(battlefield) 海战(naval battle) 陆战(land battle)... When you don't know which one to select, just take 战 :p

Oh~ interesting.... 战 just literally means "conflict (usually war)" and 仗 originated from common term for the collection of bladed, close quarter weapons that soldiers of the past used (so 打仗 just literally translates to "the clashing of weapons" if you will.) So to answer your question, after a while, these words have become synonymous with "armed conflict". It probably is the convenient translation to the word "war" in English. They can be used interchangeably these days.

They are only two characters, not words, so it's wrong questions. "war" in Chinese is 战争, "to war" is 打仗。世界大战，败仗，胜仗，they are all words. We speak words, not characters, a word maybe a character, but not every character is a word.

谢谢你的好解释！ Now I totally get it. I especially appreciate extra collocations you mentioned - they are all important and made me understand how the word "war" is used in Chinese :)

仗original means weapons, and its extended meaning is battle or war. It’s a noun. Usually we use 打仗 to express war or fight a battle, and we can use 胜仗 or 败仗 to show win or lose. 战 means war, it can be a noun, also can be a verb. When it uses as a verb, it means fight a battle. We always use 战争 to express war, but it’s greater. For example, we use 第一次世界大战 to express World War I. Hope this expression can help you.