Shemale
Shemale (sometimes she-male) is a usually derogatory term for a person who appears to be female, possessing both breasts and male genitalia.

Transgender
The term transgender (TG) was popularised in the 1970s (but implied in the 1960s) describing people who wanted to live cross-gender without sex reassignment surgery. In the 1980s the term was expanded to an umbrella term  and became popular as a means of uniting all those whose gender identity did not mesh with their gender assigned at birth. In the 1990s the term took on a political dimension as an alliance covering all who have at some point not conformed to gender norms, and the term became used to question the validity of those norms or pursue equal rights and anti-discrimination legislation, leading to its widespread usage in the media, academic world and law. The term continues to evolve.
Kathoey/Ladyboy
The term kathoey or katoey generally refers to a male-to-female transgender person or an effeminate gay male in Thailand. They are sometimes referred to as ladyboys, or as sao (or phuying) praphet song (”a second kind of woman”), or phet thee sam (third sex). The word kathoey is thought to be of Khmer origin.