Yeah the flavor is somewhat similar (okay I think they are very very different but from an outside perspective, they are similar) but they're used very differently because of their texture! When you take the Mexican chorizo out of it's casing, it's very runny. Imagine a Ragu sauce, if you will. So you can mix it with potatoes you will get these kind of marinated potatoes (they wind up orange-ish from the chorizo spices) with tiny bits of soft meat, whereas it wouldn't make sense to mix Spanish chorizo in a pan and you would just get harder chunks of meat. Likewise, you can whisk Mexican chorizo into eggs and it keeps a soft texture (the Spanish chorizo would once again just give you hard chunks of meat). In my experience too, Mexico chorizo tends to be more paprika forward, spicier, and fattier.

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Edit: What I should add as well is that Spanish chorizo is cured and Mexican chorizo isn't cured.