Retail boxes are the most accessible way to rip cards — they're lower-priced, widely distributed, and available at big-box stores like Walmart and Target. If you've ever grabbed a box of cards while grocery shopping, you've bought retail.
Retail boxes share the same base set as their higher-end hobby box counterparts, but they come with fewer guaranteed hits and chase cards. That trade-off is reflected in the price — retail is significantly cheaper.
Don't underestimate retail, though. Plenty of incredible pulls have come out of retail boxes. The odds might be lower, but when you hit, it feels even sweeter because the entry cost was so much less.