OTF and TTF are not a quality ranking
The OpenType specification allows .otf and .ttf extensions, with .otc and .ttc used for collections. Font data can include outlines, layout information and naming tables. The extension alone does not tell you whether the family has the characters or styles your project needs.
When offered several downloads, start with the publisher’s instructions for your application. Compare the family name, style and version rather than choosing the file that sounds newer. Keep the original archive so its documentation remains available.
Desktop use and web loading are different jobs
A desktop app needs a format it can install or load. A web page can define a custom face with CSS @font-face and load it from a supported source. The stylesheet associates the resource with family and style information.
This site’s real-font specimens request a font stylesheet; ordinary copied text does not include that loading setup. For your own site, use the official family’s embedding instructions or a carefully configured local font setup rather than renaming an arbitrary file.
Do not convert by changing the filename
Changing an extension does not rewrite the font data. If your application rejects a file, check its documented format support and obtain the appropriate official release. Keep conversion separate from selecting a face and review the source terms before modifying a distribution.
For a practical handoff, record the app, the exact family and the expected styles. If a teammate only needs an image, a preview PNG may be enough. If they need editable text, explain that the real font must be available in their authoring workflow.
A better file-selection checklist
First decide where the text will be edited and where it will be viewed. Then check the supported format, needed weights, scripts and included license. Finally compare a representative paragraph, heading and number sequence in that environment.
For licensing records, see the Open Font License guide. For the difference between naming a design and choosing a usable style, see typeface versus font. Start a visual comparison in the serif examples collection if you have not selected a family yet.
Your questions, answered.
Is OTF always better than TTF?
No. The extension alone is not a quality or feature ranking. Check the actual font data, app support and the needs of your project.
Can I change .ttf to .otf by renaming the file?
Renaming does not convert its internal data. Obtain a supported release or use an appropriate conversion workflow only when permitted and necessary.
Does copying text include a font file?
No. Ordinary clipboard text carries characters, not the font software needed to reproduce the same appearance elsewhere.
Sources & background
Sources supporting this page’s explanations. Practical examples are our editorial suggestions.