what are the difffernces between the different types of tzitis strings ie sefardi lubavitch etc?

Answer 1

The way in which the tzitzit are tied varies by tradition. Most of the tzitzit sold are tied after the Ashkenazi methods, with the Sefardic style being a close 2nd. They Ashkenaz and Sefard method look similar, but the Sefard loop the shamish string back under when they do each wrap. After the Sephard and Ashkenaz methods there are at least another half a dozen minor methods that have been established in the various Chassidic traditions. You will find instructions on how to tie by the three main different methods here:
http://www.begedivri.com/techelet/tying0.htm

Obviously, there is also the difference between those who tie only white tzitzit and those who have returned to the Torah command of including a string of Tekhelet (blue) in each tzitzit.

This page:
http://www.tekhelet.com/diagrams/TyingDiagramSeriesHomePage.htm
shows how to tie most of the different patterns of tzitzit, about 9 different methods in all.

There is also a difference in the thickness of the strings that can be used.

Answer 2

I am sure they are the same on all tzitis. But, the Lubavitch are not Sephardim---they are from Poland....Ashkenazim.

Answer 3

how the knots are tied. Different groups have different traditions.

Answer 4

gratvol is correct