Three rankings, three different questions
QS World University Rankings, published by Quacquarelli Symonds, put a large share of the score on reputation: surveys of academics and of employers. The rest comes from measures such as faculty-to-student ratio, citations per faculty member and the share of international staff and students.
Times Higher Education (THE) scores teaching, the research environment, research quality, international outlook and industry links across 18 indicators. It also uses a reputation survey, but leans more on publication data than QS does.
The Ulkaa Edu Rank asks a Bangladesh-specific question: how strong is each institution on the evidence available here? It combines what students actually choose (admission demand), research output, faculty qualifications, accreditation and the published QS and THE ranks. It is an independent ranking by Ulkaa, not an official one.
Webometrics, from the Cybermetrics Lab in Spain, measures something narrower: how visible and open an institution is on the web, including how much of its research is publicly available. It is useful as a signal of online presence, not of teaching quality.