Baby Center is incorrect. Each state decides what programs need to have a license. In my state, only programs that operate more than four hours need to be licensed. So a full day preschool (with AM and PM sessions) and a full day child care center both need to be licensed and follow the same criteria. Other states have different rules.
Licensing sets minimum criteria but not being licensed doesn't mean the program isn't high quality. In my state, many of the best programs only operate 3 hours 50 minutes so they don't have to have a license. There's a huge difference between a program choosing to operate half days for program reasons (for example) and one that's operating without a license because they want to operate a program that's worse than a kennel.
Each state determines the status of programs that are operated by religious institutions. Some require full licensing, others don't require licensing, and still others require licenses but some criteria are exempt.
Some states require (legally) unlicensed programs to have health and safety inspections and some don't. Some states (and/or individual programs) require every teacher to be First Aid/CPR certified. Other states require one person in each classrooms. Others require that at least one person in the building be certified.
Playground safety standards vary widely but generally permanent equipment (like swings and climbers) need to have certain amount of uncompacted mulch (or other allowed surfacing like pea gravel, solid or shredded rubber, sand, etc.) underneath. The depth depends on the height of the playstructure and the rules of the state. But, some places don't require soft surfacing under moveable structures (for example, Little Tikes climbers.)
You really need to look at a program, spend time there, and decide what works best for your family.