Comparison of iWork and Microsoft Office
From Mac Guides
Of the two suites, selling for $79/£55, iWork is significantly less expensive than Office. Educational customers are entitled to a discount on this price. Microsoft Office on the other hand starts at $150/£107 for the Home and Student edition which includes Word, Excel, Powerpoint and Entourage. The more expensive Standard Edition costs $400/£356 (upgrade $240), which includes some automator actions as well as better Microsoft Exchange support which is useful for business customers. Finally, the Media Edition costs $500/£450 (upgrade $300) which as well as the automator actions and better Microsoft Exchange supports Microsoft Expression Media.
All new Macs are shipped with time-limited but fully-featured installs of both Office and iWork. These preview versions can also be downloaded for free from Microsoft and Apple, respectively. Trying the preview versions can be the best way to determine which one is most suitable for your needs.
File Format Compatibility
Microsoft Office for Mac has excellent support for Microsoft Office for Windows files, though there can sometimes be minor compatibility issues, Office 2008 can import both traditional Word documents and new Office 2007 "Open XML" Office files. iWork also has support for both traditional and "Open XML" Office Files but can have moderate compatibility issues with Word files containing complex formatting or Word-specific features — as will be the case with all word processors which must reverse-engineer Microsoft's file formats or don't include the exact same feature set. Some very old Word files will not open in Pages, but they will generally open in TextEdit. If you use iWork and you want to send files to Windows users that don't require editing it is probably better to send them as a PDF.
Although iWork can open and save Office files, file management can be inconvenient. iWork automatically converts Office files to iWork formats upon opening, so when saving, users must "export" files to Office format, even if they were in Office format to begin with.
Pages vs Word
Both Pages and Word are perfectly adequate word processor and page layout programs; however Word generally has more features, and the approach to the user interface taken by Apple and Microsoft are quite different. Both Word and Pages allow you to type, colour, style text with fixed style, have auto-correction and can track changes. On balance Pages probably has better templates though Word's are fairly good too. Pages includes a powerful template-making feature, and handles the creation of paragraph and text styles with more ease than Word. Pages is weaker on footnotes and endnotes (you have to choose one or the other), it also lacks citation manager. Additionally, unlike Microsoft Word, it doesn't include a built in equation editor. However if you install LaTeX you can use LaTeXiT with iWork which may be preferable as it is much faster to use than Word's equation editor. When dealing with large documents Pages can take significantly more RAM. Most users find that Pages is faster than Word. Many users have noticed that Word often "lags" when typing, sometimes by several seconds between typing and seeing text appear.
Numbers vs Excel
Numbers and Excel are both spreadsheet programs though they are designed to be used in different ways. Numbers, currently at version 1.0, has far fewer features than Excel, although its use of multiple tables per sheet is excellent for basic tasks, such budgeting and holiday itineraries as you can use multiple tables per page as well as easily apply colour schemes and summation rows to each table. Excel only supports a single, essentially infinitely sized table per sheet, however is more suitable for demanding business, professional and academic uses, while handling the simpler tasks reasonably well.
Unlike Numbers, Excel supports advanced charting and enables plotting multiple lines of data at once as well as error bars. Excel also handles true scatter plots and curve-fitting. While Numbers' charting options are limited, many would agree that Numbers' charts look better than those from Excel. While charting options in Numbers are lacking, Numbers does support all the same formula commands as Excel, meaning that sophisticated calculations are possible in Numbers.
As with Pages and Word, Apple and Microsoft take a very different approach to the user interface in Numbers and Excel. Veteran Excel users will likely require some adjustment transitioning to Numbers. The current version of Numbers performs very slowly with large data sets. When exporting from Numbers to Excel, each table becomes a separate worksheet in Excel, and a new worksheet is added indicating that the work has been exported. This can be inconvenient when collaborating with others who use Excel.
Keynote vs Powerpoint
Keynote and PowerPoint are both presentation creating applications. Keynote is widely regarded as being superior and was used by Al Gore to create "An Inconvenient Truth" as well as for Steve Jobs' Keynote presentations at MacWorld and WWDC as well as other Apple Special Events. Keynote features a wide array of templates and transition effects. Keynote can open PowerPoint files, although some reformatting will probably be required after conversion to the Keynote format. Keynote exports presentations in several file formats, including QuickTime and Flash. Keynote files cannot directly be opened in Windows and as such you have to convert the file first which depending on the route can cause loss of formatting / transitions.
Mail/iCal vs Entourage