This study was conducted to examine how various task types affect the extent to which learners engage in form-related changes (FRC) and meaning-related changes(MRC). To this end,15 Iranian language learners (9 female and 6 male) participated in instruction sessions in which they learned how to self-correct and peer-correct three writing tasks,namely; argumentative, informative and analytical. Etherpad package was used to facilitate the communication among the learners as they shared their responses and feedback on each other's writings. Data analysis indicated more instances of peer-correction (54{\%}) compared to those of self-correction (46{\%}) in the three task types. The results of a Chi-square analysis illustrated that the difference in the instances of corrections produced was statistically significant (X2=10.890, p=0.00). In this regard, the results indicated that the number of corrections produced in the analytical task was higher than that of other tasks. Another Chi-square test (Chi-Sq = 6.754, DF = 2, P-Value = 0.034) proved that the participants in all task types made statistically significant changes in meaning-related aspects compared to the changes they made to the formal ones in their written products. A t-test analysis revealed that learners' focus between form and structure was not significantly different whether they work individually or collaboratively. (P-value = 0.3 for argumentative task, P-value = 0.26 for analytical task). However the analysis showed that the emphasis of accuracy and meanings (p-value =0.031 for argumentative task, P-value = 0.033) increased when they worked in groups. The findings of an interview revealed that most of the interviewees agreed that the writing and editing in collaboration with peers were a positive and useful experience.