Explain the difference between a personal geodatabase and a file geodatabase?

For difference btw Personal Geodatabase:

1. for their description: File Geodatabase  is a collection of various types of GIS dataset by Arc Catalog platform and held in file system folder, this is recommended  native data format for ArcGIS stored and managed in a file system folder.  while Personal Geodatabase is originally data format for ArcGIS geodatabases stored and managed in Microsoft Access data files, this is limited in size and tied to the windows operating system.

2. Number of Users: File Geodatabase has Single user and small work-groups Some readers and one writer per feature dataset, standalone feature class or table. Concurrent use of any specific file eventually degrades for large numbers of readers. Personal Geodatabase has Single user and small workgroups with smaller datasets  Some readers and one writer. Concurrent use eventually degrades for large numbers of readers.

3. Storage Format:  File Geodatabase (Each dataset is a separate file on disk  A file geodatabase is a file folder that holds its dataset files). Personal Geodatabase ( All the contents in each personal geodatabase are held in a single Microsoft Access file (.mdb).

This answer have strongest reference from Esri. our knowledge sources. 

Personal geodatabase is using to store the MS access data, with relatively less storage and is for a single user. On the other hand file geodatabase can store multiple file types, each stored as separate file and each dataset can be of a whooping 1TB storage.