MS thesis defense equivalent to publishing as a MS student? When applying to Ph.D. at the top 10 programs in the US, does MS thesis defended to committee members have the same weight as publishing paper as a MS student? Or am I at the disadvantage of not having any publications? 

I was in EE working in Physics department in the field of Quantum Optics.
No, a defense is not equivalent to a publication. A defense may just be something required by university rules and takes some of the responsibility and guidance from the advisor and gives it to others. Some such theses are available in, say, the university library, but that isn't the same as journal (or conference) publication which is more public by definition. 

The defense is usually a closed system within a department, thought there could be external members of the committee. But a publication has been vetted by independent referees and an editor and it is done in competition with other papers. 

And if a defense is required there is no reason that you can't also do a paper if the results are good. It might not be the thesis itself, but could be based on the work. 

A publication is almost certainly better if you plan a career as an academic, but possibly not by a tremendous amount. The admissions committee may actually do some (probably minor) evaluation of the work in either case. But having a publication in a reputable place will relieve them of some of the burden of judgement.