When officers entered the back of a residential building, what is the difference between a police search warrant and a search warrant?

The back building had a single door and window, however, officers could not see into the building before they made entry. While substantial evidence was offered to demonstrate that, upon entry, it was apparent the back building was a dwelling, no evidence suggested the officers could make that determination solely from an observation of the exterior. Officers knocked and announced their presence, declaring they had a search warrant for the premises, which indicated they believed the warrant in fact encompassed the back building. Once they entered and detained defendants, it was apparent the back building was a dwelling. Upon learning it also may have a separate address; the officers simply froze the residence and applied for a second search warrant. It is important to note the officers did not search the back building until they obtained the second warrant. While the officers did observe the suspected methamphetamine upon entry of the back building, it appears undisputed the contraband was in plain sight. (Horton v. California (1990) 496 U.S. 128, 133 ["If an article is already in plain view, neither its observation nor its seizure would involve any invasion of privacy"].) As such, the observation of the suspected methamphetamine was properly placed in the affidavit.