Difference between na().drop() and filter(col.isNotNull) (Apache Spark)

With df.na.drop() you drop the rows containing any null or NaN values.

With df.filter(df.col("onlyColumnInOneColumnDataFrame").isNotNull()) you drop those rows which have null only in the column onlyColumnInOneColumnDataFrame.

If you would want to achieve the same thing, that would be df.na.drop(["onlyColumnInOneColumnDataFrame"]).