Thank you so much, that helped a lot.

Dear Tadesse, about your question.

That you have a nice day.

Gustavo

Please see http://eurheartj.oxfordjournals.org/content/30/4/404

Figure 1

Chemical structure of cholesterol, sitosterol (plant sterol), and sitostanol (plant stanol). Both plant sterols and plant stanols differ from cholesterol only in the side chain attached to the sterol ring. Plant stanols are saturated plant sterols without a double bond in the sterol ring. Due to their saturation status, plant stanols are less effectively absorbed. Esterified plant sterols and plant stanols are supplemented in ‘nutraceuticals’ to reduce serum cholesterol levels 

Sterol is general term as all those compound have similar ring structure. Difference is modification in side chain slight modification in ring and lead to wide range of compounds. Cholesterol is one of the major component of membrane structure whereas also a major part of lipoproteins. Bacteria do not have sterol or cholesterol and some very minor conc of some form sterol is reported in certain specific prokaryotes. For detail what different impact these sterol can have: See some of my own publications. JBC, JLR  

 Dear Tadesse:See the trans fatty acids concentrations  in margarines. It is very important in  human Nutrition .