"VRLA" stands for Valve Regulated Lead Acid, "MF" stands for Maintenance-Free, "AGM" stands for Absorbed Glass Mat, and "SLA" stands for Sealed Lead Acid. All 4 of these terms basically refer to the same type of battery. An example of this would be the Yuasa YTX series. These batteries are typically all black in color.
"Standard SLI" (Starting, Lighting and Ignition) refers to any standard, non-sealed battery. In this case SLI refers to older style batteries used for powersports type vehicles. An example of this battery would be Yuasa's 12N-series or YB-series (Yumicron) type batteries. These batteries are typically white with a black top, and with yellow or green acid filling caps.