Zygote is the fusion of the male and female gametes that is the sperms and the egg in the oviduct/Fallopian tube
foetus is the implantation and the nourishment of the developing of the zygote in the uterus 
Sir u didn't told what is foetus
A foetus is a stage in the development of a baby in uterus and the part of the body can be identified easily and distinctly.
Foetus:the embryo continue to develop in the uterus. It gradually develops body parts such as hands, legs, eyes, ears, etc. From eight weeks till the birth the baby is called the foetus. Zygote: the process of fusion of sperm with ovum is called fertilisation. Zygote is formed after fertilisation.