When a Maryland state senator said he wanted to make changes to the charter school agreement between College Park Academy , which has ties to the University of Maryland and the Prince George’s County school system, parents wondered what that would mean for the school’s future.

Sen. James C. Rosapepe (D-Prince George’s) — who serves as chairman of College Park Academy, which opened two years ago to great fanfare — tried to reassure parents during a recent community meeting that there would be no impact on learning. He said a change to make College Park Academy a “contract school” would not affect the school’s curriculum, its teachers or its governance structure.

“Nothing will change regarding the classes or the school,” Rosapepe said as parents bombarded him with questions about the request.

“What is a contract school?” a frustrated parent asked.

Unlike charters, which enrolled 2.7 million students in more than 6,400 schools across the country last year, contract schools are a relatively new classification, one that provides a school district with more flexibility than it has with a charter school.

Both are publicly funded, but who attends the schools and the system for accountability differs.

In Prince George’s, charter schools operate under an agreement with the school system. They are accountable to their sponsors, local school board and the state’s education agency. And they can be closed for failure or poor operating practices. Contract schools in the county would be under contract with the local school system and would be accountable only to the local school district.

Charters are open to all students. A contract school could require testing as part of admission or target specific students, according to county school officials.

Todd Ziebarth, senior vice president of state advocacy and support at the National Alliance for Public Charter Schools, said contract schools are “often a response to the influx of charter schools.” Ziebarth said such schools have opened using a variety of terms in recent years: In Boston, they are called pilot schools, and in Colorado, they are called innovation schools.

There were 52 charter schools in Maryland last year, according to the charter schools alliance. But there were less than a handful of contract schools in Maryland, state officials said. None were located in Prince George’s or Montgomery counties, the state’s two largest school districts.

Officials said another difference between a charter and a contract school is in the way they originate. Charters are generally founded within the community — with support from a group of parents, a group of teachers, or a national charter organization — while contract schools are generally operated from the top down at the direction of school district officials.

Similar to a charter school, a contract school is run by an independent group. But unlike a charter, a contract school in Prince George’s would not have to adhere to the state charter school regulations, including rules regarding enrollment.

Rosapepe wants to reserve a percentage of seats at College Park Academy for children of University of Maryland employees who live in College Park. He could make changes to enrollment requirements if the school receives a waiver from the charter laws or if the school becomes a contract school.

Prince George’s County Schools Chief Kevin M. Maxwell told Rosapepe last month that he would not recommend that College Park Academy be reclassified unless improvements are made to its governance.

College Park Academy isn’t the only school in Prince George’s that has considered the new classification. Draft documents for two new international high schools, which are being created to support English-language learners, identified the schools as contract schools, but school district officials say the high schools will not be given that designation.