what is glushkov NFA. What is the difference between Glushkov NFA and Thompson NFA?
The most significant difference is that Glushkov's NFA does not use $\epsilon$-transitions.  Very roughly, the algorithm indexes the characters in the regular expression from left to right.  Each state in the NFA is a subset of possible indices of the last character read from the input string.

Glushkov's construction [3] is described in detail in Aho, Sethi, and Ullman's classical compiler textbook, aka "The Dragon Book" [1].  The same construction was also described earlier by McNaughton and Yamada [4] and later  by Berry and Sethi [2], so you may find it easier to search under those names.


A. V. Aho, R. Sethi, and J. D. Ullman.  Compilers: Principles, Techniques, and Tools. Addison-Wesley, 1988.
G. Berry and R. Sethi. From regular expressions to deterministic automata.  Theoretical Computer Science 48:117–126, 1986.
V. M. Glushov.  The abstract theory of automata.  Russian Mathematical Surveys 16:1–53, 1961.
R. McNaughton and H. Yamada.  Regular expressions and state graphs for automata.  IEEE Trans. Electronic Computers 9(1):39–47, 1960.