godan verb (-u), transitive verb
say to each other; exchange words
Neutral reciprocal action: two or more people say something to each other, often with a specific content like jokes or greetings.
友達と冗談を言い合った。
I exchanged jokes with my friend.
彼らは別れ際に「またね」と言い合った
They said 'see you later' to each other as they parted.
godan verb (-u), intransitive verb
Reciprocal conflict: two or more people argue or exchange heated words. Often implies a disagreement or fight.
兄弟がおもちゃのことで言い合っている。
The siblings are quarreling over a toy.
会議で意見が対立して言い合いになった。
Opinions clashed at the meeting and it turned into an argument.