Answer
Constitutional isomers.
Work Step by Step
They are constitutional isomers. Count the number of Carbons and the hydrogens. In the given compounds, the molecular formula of both the compounds is $C_7H_{12}$. However, the connectivity of the $CH_3$ is different. On the left one the $CH_3$ is connected to the carbon with double bond and on the right one the $CH_3$ is not connected to the carbon with double bond.
