qgis - How to check what changed inside the updated shapefile?

I am using different shapefiles from open data in Switzerland. They have just updated the whole set. My question is: how to compared two layers (new and old version)? I would like to know the differences in geometry, as well as attributes. In the data there are points, lines and polygons and some of the sets contains a big amount of features (more than 300 000 elements).

I have already checked all the simillar questions, but they all focus on creating the third layer with differences or particular layer example.

What I want to know is just what has been changed.

I am working with QGIS 2.14.3 and i am familiar with python.

Answer

It is not with QGIS or PyQGIS, but if you know Python and the modules Pandas and GeoPandas (Python 2.7 and 3.x), it is easy using the solution of Outputting difference in two pandas dataframes side by side - highlighting the difference if the two shapefiles have the same schema and the same record indexes

import geopandas as gp
# convert shapefiles to GeoDataFrame
old = gp.GeoDataFrame.from_file("shape_old.shp")

new = gp.GeoDataFrame.from_file("shape_new.shp")
old

new  

import numpy as np
import pandas as pd
# which entries have changed

ne_stacked = (old != new).stack()
changed = ne_stacked[ne_stacked]
changed.index.names = ['id', 'col']
print changed
id  col     
0   geometry    True
    test        True
1   ensayo      True
2   ensayo      True
    geometry    True

Compare the columns which has been changed.

difference_locations = np.where(old != new)
changed_from = old.values[difference_locations]
changed_to = new.values[difference_locations]
pd.DataFrame({'from': changed_from, 'to': changed_to}, index=changed.index)

But with more than 300 000 elements...