Is Descartes's concept of God similar to that of Spinoza? If it is so, what are those similarities?

Answer 1

yes and no

they are similiar in that they both reject the conventional image of the godhead [for their time and culture]

that is, in their understanding of the essence of the godhead,
its ineffability, its attainability/understandability,
and its interpersonal causal relationship with humanity....

but between the two...there a priori assumptions lead them to quite different conclusions...

try reading "A History of God" by Armstrong

Answer 2

Do you proooooomise you're not just trying to cheat on a paper? :)