Service Alerts will notify you of long-term disruptions and detours in place, including reroutes, bus bridges, and moved/closed bus stops.
On the other hand, the Real-Time feature will be able to provide you with up-to-date information on trip updates (like last-minute cancellations) and vehicle positions (like the current or "real" time for expected bus/train arrivals).
The Real-Time feature can be found either:
1. under the Route schedules
2. under the Real-Time Trip Planner
For Route schedules, please use the "Show/Hide Real Time" button to toggle back and forth between Real and expected times.