I've had the opportunity to teach at both a regular public school and a charter school. A charter school is a free public school. Enrollment is just capped and enrollment selection is usually based on a lottery selection.
No two charter schools are alike. Each one has a different community feel and a different emphasis. But that's the thing you get at a charter that you don't find at a regular school: a community. Charter schools have a small student body. There seems to be more of a smaller community feel as well as a stronger sense of school culture. As a teacher, I knew my students very well and sometimes, had them in my class for a few years. I knew the student's siblings and parents much more than in a regular school. I felt like I had a much closer relationship with my charter students and families than in a regular school. Students can't get lost in a charter school. Each student has a name, personality and individual needs.
There also seems to be greater flexibility in a charter. These schools are not afraid to break the mold and try new things. They offer parents a choice in their student's education.
Regular public schools, at least on Utah, are much larger than charters. Students can get lost in the huge junior highs and high schools. However, there is much more variety in classes, teacher personalities and extra curricular activities. But regular schools feel like an educational machine with compartmentalized classes held to the relentless ticking clock (45-50 minute classes.) There seems to be a bigger emphasis on testing in the regular schools and even teaching to the test. Student test scores reflect heavily on the teacher, but there is really no student accountability for these standardized tests.
The workload for teachers is greater at a charter. Smaller schools demand that teachers wear lots of different hats which requires a great deal more preparation. At my charter school there was much more freedom than at my current school.
Charter schools typically have very supportive parents that are very involved which is good and bad (helicopters parents--bad, supportive parents--good). The board (at the charter) was made up of parents which was difficult because many times they had these unrealistic, grandiose ideas but they weren't educators so they didn't realize how difficult the implementation of these dreams would be.
In a regular school, policies and procedures and curriculum are pretty tried and true. Sometimes rigidly so.
I don't know that one type is any better than the other. There are pros and cons to both. I do think it's liberating and wonderful that there is a CHOICE!