A compelling presentation requires good content that's well laid out and visually informative. PowerPoint has many excellent tools to help you reach that goal, but diagrams aren't one of its strengths. If you need a diagram to get your point across, you're probably better off creating it in Visio.
Visio vs. PowerPoint
Visio and PowerPoint are both part of the extended Microsoft Office family. PowerPoint creates and presents slideshows and can be used for anything from a middle school science presentation to a high-stakes corporate sales pitch.
Visio is a specialized tool for creating flowcharts and diagrams. They can be as simple as an organizational chart for a department with a dozen people or as complex as the map of a new processor chip's functions.
There's a degree of overlap between PowerPoint and Visio. You can create simple graphics in PowerPoint and simple presentations in Visio, but if you need a top-quality diagram in a full-featured slide show, your best bet is to start with a Visio graphic and import it into PowerPoint.
Using Slide Snippets
There's a streamlined way to export Visio to PowerPoint, as long as you're an Office 365 user who subscribes to Visio Online Plan 2. It's a feature called Slide Snippets.
Creating a snippet is much like cropping a photo. First, click View and choose Slide Snippets Pane. The new pane appears to the right of the main window. Click Add in the Snippets pane, and a resizable box appears over the diagram. Move it and resize it until you're happy with the portion of the image you see in the Snippets pane and then type a title for the image.
To create additional Snippets from the same diagram, repeat the process. When you're finished, click Export to create your PowerPoint deck. Alternatively, you could choose Create PowerPoint Presentation from the File tab.
A Nice Extra Feature
If you're taking multiple Snippets from the same diagram, overlap them slightly. When you export them to PowerPoint, the images use PowerPoint's morphing slide transition. This feature requires the latest subscription version of PowerPoint. If you're using a non-subscription version of PowerPoint or if you don't overlap the Snippets, you'll get the standard transition.
Copy From Visio to PowerPoint
Slide Snippets aren't available in other versions of Visio. The workaround is to copy and paste into PowerPoint.
Either open Visio's Home tab and choose Copy or use the Ctrl+C keyboard shortcut. If it's a multipage image, make sure the page you want to use in your PowerPoint slide is active. You can then paste it into your PowerPoint slide deck.
If you paste it using the Paste command or the Ctrl+V keyboard shortcut, as Microsoft's support page suggests, your diagram may look unacceptably blocky and low-resolution. There's a reason for that and an easy workaround.
Raster, Vector and Pasting Correctly
Computers save graphics files in one of two ways. One is to save each pixel that makes up an image, so it can be recreated exactly. Those are raster graphics, the type of image PowerPoint uses. Their shortcoming is that the graphics file is created at a specific size. If you make it larger, the image becomes blurry and has rough, boxy edges.
Vector graphics save mathematical instructions for recreating the image, not the image itself. Vector images, the kind used in Visio, are smaller and can be redrawn cleanly at any size. However, if you use Ctrl+V to paste into PowerPoint, the vector image converts into a raster PowerPoint graphic and loses its resolution and clarity.
The trick is to right-click with your mouse at the spot where you want to insert the diagram and choose Paste Image. If you prefer keyboard shortcuts to mouse clicks, press the Alt key to bring up the ribbon and then H for the Home tab, V for paste and U to paste as an image object. This action embeds the diagram, meaning it remains a vector graphic and stays linked to Visio even though it's in a PowerPoint slide show.