Applications like PowerPoint, Keynote and Google Presentation are designed to create a sequence (often referred to as a "stack" or "deck") of "slides." These slides can contain, text, images, audio and video.
There is good online document of all these applications. For information on how best to use these tools in presentations, see:
PowerPoint is available for both Macs and PCs, but there are difference, particularly with respect to audio and video. For more information on these differences, see:
KeyNote is a Mac only desktop application. KeyNote can import and export as PowerPoint and PDF
Google Presentation is a web application that is part of Google Apps. As such it works the same on Macs and PCs. Presentations created with Google Presentation can also be downloaded in PowerPoint and PDF format