Well, both software programs i.e. Notepad and Word Pad are used for text editing purpose for Windows OS. The Notepad is faster than Word Pad as Notepad restricts with formatting options and is good for creating basic text file and paragraph creation line breaking can be done easily on Notepad.
The Word Pad is good for creating a text file with many options provided for formatting of text.
Notepad is also useful for creating web pages while Word pad is only used for creating a text file and saving the file in text option or rich text format as well. When you try to copy paste the text from notepad to other notepad files than you can suffer improper formatting of a document which you will not find in case of Word.
So, in case of proper formatting and more options for font style and size you can go for Word Pad. But for basic document creation or creation of HTML pages notepad is a good option and of course faster than Word Pad.
Notepad is simple to use with limited options whereas Word pad can be complicated to use to a vast range of options of formatting. All this simple and basic functions makes notepad faster than Word pad in MS Windows.