What is the difference between parenthesis and no parenthesis in head and tail?

[snippsat]

Thank you! It looks like Python still has that address and pointer stuff

This has nothing to do about pointer stuff,that Python don't have.
You can assign to df.columns = that's why it's not a function call.
df.head() is just a function call to get rows,set to default 5.
Eg:

import pandas as pd

df = pd.DataFrame({'a':[1,2,3,4], 'b': [10,20,30,40], 'c': [5,6,7,8], 'd': [50,60,70,80]})
# Set columns,would look bad with ()
df.columns = ['a', 'b', 'c', 'd']
print(df)

a b c d
0 1 10 5 50
1 2 20 6 60
2 3 30 7 70
3 4 40 8 80

# caLL 2 rows
print(df.head(2))

a b c d
0 1 10 5 50
1 2 20 6 60

I think in Java you don't get this kind of address problem.

It's not a problem as explained,
Java has it's own bundle of verbose stupidness