I learned that the complex representations $$\rho: \operatorname{Spin}(n, {\mathbb C})\to SL(N, {\mathbb C})$$ of complex Spin groups $\operatorname{Spin}(n, {\mathbb C})$ helps to study the compact Spin subgroup $\operatorname{Spin}(n, {\mathbb R}) := Spin(n)$.
The restriction of such a representation to the compact Spin subgroup $Spin(n)$ is automatically unitarizable, i.e. the image is contained in an $SU(N)$ (or its conjugate? please correct me?).
A representation $\rho$ is called spinoral (or simply spin) if it does not descend to the orthogonal group $SO(n, {\mathbb C})$ (equivalently, $\rho: \operatorname{Spin}(n, {\mathbb C})\to SL(N, {\mathbb C})$ is injective).
Then I heard that there are also half-spin or semi-spin representations: They are also spinoral.
Could you explain how the spin representations differed by the semi-spin representations?