These are action methods that return data -

first() : Returns the very first row of the dataframe as a single row.

head() : This does the same as first(), returns the first row

head(n): Returns an array or list of the first n rows

take(n): Similar to head(n), it retrieves the first n rows and returns them as an array

These action items display data-

show(): Prints the first 20 rows in a tabular format

show(n): Prints the first n rows in a tabular format