What is the difference between free digital comics and digital comics available through subscription services?

Free digital comics are typically limited in scope – often single promotional issues, samplers, or older titles provided as part of library services or special events. They don't usually include new releases or entire extensive back catalogs. In contrast, digital comic subscription services (like DC Universe Infinite) offer vast libraries of comics, often including thousands of issues, collected editions, and access to new releases after a specific delay, all for a recurring fee. The key difference lies in the breadth of content and the availability of current material.