Nowadays three-dimensional (3D) multi-user virtual worlds (VWs) are the most well-known candidate platforms in Higher education. Despite the growing number of notable studies that have presented VWs as valuable platforms for the e-Education, there is still a paucity of a comparative study in order to be determined the degree of the students' engagement in constructionist-collaborative learning scenarios. Concurrently, it seems imperative the need for educators and scholars to identify how can VWs influence students' engagement in contemporary and reliable instructional formats, mainly on blended or online settings for university-level courses. In this study the effects of students' achievements were measured by comparing the degree of students' engagement from two student groups (graduate and undergraduate) enrolled in two different instructional formats (blended/online) held in Second Life (SL) to become learning content developers. The purpose of the current research is to present results from the comparative study of one hundred twenty-five (125) students that finally attended in order to be measured their engagement overall as a multi-dimensional construct consisting of the emotional, behavioral and cognitive factors. The study findings from the quantitative analysis have disclosed that graduate students who participated in online courses achieved more positive learning outcomes and as a result the degree of their engagement was significantly increased than those who enrolled with the blended. In these circumstances there are raised some fundamental educational implications which are also discussed.