Reddit has provided rich data on mental health discourse. The present study uses 40,335 online posts from Reddit communities to investigate how language can contribute to the understanding of PTSD and C-PTSD. The results showed distinct language patterns in the use of first-person pronouns, cognitive processing, and emotion words, suggesting that they are separate disorders with different effects on survivors. Further, while some social media studies have differentiated submissions and comments, few have investigated the language changes between these contexts. Post-hoc results showed a clear distinction between two contexts across several linguistic markers. Discussion and future directions are explored.