Reductive ozonolysis of ${\left({\mathrm{CH}}_3\right)}_2\mathrm{C}=\mathrm{C}{\left({\mathrm{CH}}_3\right)}_2$ followed by hydrolysis gives 

Reductive ozonolysis of ${\left({\mathrm{CH}}_3\right)}_2\mathrm{C}=\mathrm{C}{\left({\mathrm{CH}}_3\right)}_2$ followed by hydrolysis gives only one type of ketones because of symmetry across the $\mathrm{C}=\mathrm{C}$ and bonding of two same alkyl groups $\left({\mathrm{CH}}_3\right)$ with both the carbons bonded through double bond.