Sometimes content that has been cut and pasted into the site will keep the source formatting which in turn results in some content looking different than others.
There will often be formatting hidden within the text, implementing different fonts, spacing, and text sizes. A very common cause of this is when people paste content in from Microsoft Word. However, sometimes you'll notice that text appears in a very different size or font than it normally does. The Tithe.ly Sites text editor comes with three pre-formatted text sizes: Main headline, sub-headline, and standard paragraph.