Difference between tableau extensions .twb and .twbx

Twbx:

1. .twbx file is a Tableau Packaged Workbook, meaning it is the original .twb file grouped together with the datasource(s) in one package. 
2.  .twbx files can be considered analogous to specialized zip files, in which these “zip” files contain all the information necessary to work in Tableau.   
3. The primary advantage to using .twbx files is that analysis can be performed without network/internet connections to your data because your data is already present on your computer in this packaged file.

Twb:

1. The .twb file alone is not enough to perform any analysis because it only contains Tableau’s instructions for interacting with a datasource.  
2. In actuality, .twb files are XML files specially tailored to interact with datasources.
3. They are custom built to make the awesome visualizations that Tableau generates.  Here you can see a picture of a .twb file opened in Notepad++.

What is the Dimensions and Measures?

Dimension: A dimension is a field that can be considered an independent variable.

Dimensions typically produce headers when added to the rows or columns shelves in the view. By default, Tableau treats any field containing qualitative, categorical information as a dimension. This includes, for instance, any field with text or dates values.

This means that a measure can be aggregated for each value of the dimension. For instance, you might calculate the Sum of “Sales” for every “State”. In this case the State field is acting as a dimension because you want to aggregate sales for each state. The values of Sales are dependent on the State, so State is an independent field and Sales is a dependent field.

Measure:A measure is a field that is a dependent variable; that is, its value is a function of one or more dimensions.

Measures typically produce axes when added to the rows or columns shelves. By default, Tableau treats any field containing numeric (quantitative) information as a measure.

This means that a measure is a function of other dimensions placed on the worksheet. For instance, you might calculate the Sum of “Sales” for every “State”. In this case, the Sales field is acting as a measure because you want to aggregate the field for each state. But measures could also result in a non-numeric result. For instance, you might create a calculated measure called “Sales Rating” that results in the word “Good” if sales are good and “Bad” otherwise. In this case the “Sales Rating” field acts as a measure even though it produces a non-numeric result. It is considered a measure because it is a function of the dimensions in the view.