Google Calendar app entries on Android Device inconsistent with web browser entries

I cannot make sense of the entries on my Google Calendar for android application. When compared with the web version of Google Calendar (see screenshots below), I can see the following differences:

• 
  

  Google Calendar for Android shows two accounts (both are associated with exactly the same e-mail address, and this is exactly the same e-mail address I use to access Google Calendar via a web browser). To me this is confusing: why two accounts with the same name? And why two of them, when on the PC only one of them shows up?

  
  


• 
  

  Secondly, the entries (the calendar names, if this is what they are), are different. The Android app displays "Events" (but I have no calendar called Events on the web interface), Samsung Calendar (no clue as to what this is), "My calendar" (but on the web interface I have "My calendars", i.e., more than one), etc... you can see that besides "Birthdays" and "Holidays" I cannot see all the other calendars which can be seen and I have added via the web interface.

  
  

Can someone please explain these differences?