Each font or style (italics or bold) should be used consistently throughout your presentation. While a different font face or color is a simple way of highlighting certain terms you want for focus, too much of it will do exactly the opposite and distract the audience.
❌ Figure: Bad example - Different fonts and styles of a flourished type face used. Makes your slide hard to read for the audience
✅ Figure: Good example - Even though there are a lot of words, the important ones are clear because there is only one font used, with colors to emphasize