While the actual drugs tend to be the same throughout the world, the names given to them vary somewhat from country to country. Once you have found out the generic name for the drug you are interested in, you can probably find out all (or more...) than you want to know about it by searching for it on http://rxlist.com

Conjugated oestrogens have been the most widely used type of natural oestrogen and most of the safety information we have about HRT is obtained from the use of these tablets. Conjugated oestrogens are extracted from the urine of pregnant mares and, although there has been some concern about the well being of these animals, there is also reassurance from the pharmaceutical company that the farming conditions are satisfactory. It is treatment with these tablets that gives us most of the information on the prevention of oseoporosis and heart disease. 

Most other tablet forms of HRT contain oestrodiol valerate or a similar compound and these tablets are extracted from soya beans. While these preparations appear to be the same strength as conjugated oestrogen tablets, we do not yet have the many years of scientific research to be certain of the risks and benefits of this treatment although they are likely to be as effective as conjugated oestrogens. Two new preparations in this group have recently been introduced to reduce the number of menstrual periods in women on hormone replacement therapy. Tridestra provides a period every three months and Kliofem provides continuous oestrogen and progesterone tablets, resulting in no periods in some women. 

All oral contraceptive pills contain ethinyloestradiol, a strong synthetic oestrogen designed to prevent ovulation. Oral contraceptive pills have often been used as HRT in young women. The oral contraceptive pills however, because they are stronger than natural oestrogens, do carry a small increased risk of blood clotting (thrombosis) which does not occur with oestradiol valerate or conjugated oestrogens. For many women with oestrogen deficiency, the oral contraceptives may be unnecessarily strong for use as HRT.