The main difference of alkene and alkyne is the number bonds that they have between two carbon atoms. Alkene has a `C=C` or double bond while alkyne has `C-=C` or triple bond in the structure.
Cis and trans notation for isomer is used in alkenes in determining the orientation of the functional groups attached in the `C=C` bond. When the substituent groups are oriented in the same direction, it is named as cis isomer. If opposite, trans isomer.
Let me show you the difference between the cis and trans isomers of 1,2-dichloroethene. Notice the orientation of the Cl substituents.
alkene means double bond found and 1 unsaturation alkyne means triple bond found and 2 unnsatration cis isomer the functional group are in same phase trans isomer the group will be opp. to it and in alternate direction i encircle the funtion group to which i m refering to say cis or trans