Overview of Resource Sources
There are some significant differences between these two providers. These can be summarised as follows:
Google Books allow you to search for a word or phrase within all of their volumes. However, you may not be able to download a book at the end of your search as Google interprets copyright limitations somewhat differently depending on where you live in the world. Where a book is available for download it is likely to be in pdf format, although Google has recently started to add some other formats. A book from Google (in pdf format) will not be searchable for a word or phrase in the way that their website allows. Also Google reduces most pages to black and white images which affects the quality of illustrations. Books scanned by Google in the earlier years of their project were often of very mixed quality. However, they seem to have realised this and more recent scans are better. They also appear to have rescanned some of the earlier, defective, titles.
Internet Archive Texts allow you to search for a book, but do not immediately allow you to search for a word of phrase within that book. However, when you find a title of interest then you are able to click on the 'Read Online' link in the 'View the book' box on the left of the page. When you have done this then you will be able both to read the book and to search its contents using the search pane on the right side of the page. From the original page (use your browser's back button to return) you are able to download a copy, and usually in several formats including pdf, djvu and txt. Internet Archive (IA) has also started to make titles available in some other formats. A book downloaded from IA is always searchable, and additionally is usually scanned in colour, thus retaining the quality of illustrations. An exception to the colour rule is the large number of books that were originally scanned by Google. These titles are searchable (although the Google originals are not), and some titles not available from Google are available from IA!You may also find our Download Tips helpful.