Collects storm water from street drains and house gutters
Eventually leads to the Bay
2 - the sanitary sewer
Carries wastewater (sewage)
Is connected to your home's plumbing fixtures (toilets, sinks, laundry)
Leads to a sewage treatment plant
Your home's sewer is connected to the sewer "main" (large pipe often running under the street) via a "lateral" pipe extending from the home (upper lateral), across the property line (lower lateral) and then into the main.
In many communities homeowners are responsible for maintaining the "upper" lateral that runs under their property. The city or sewer district is responsible for maintaining the "lower" lateral and the main.