To clarify, are you talking about the difference between slavery and indenture, or the enslavement of native Americans in the Americas by colonists?

Assuming you mean indentured servitude, historians distinguish among several kinds of unfree labor, and while indentured servants are unfree, they also have legal rights and retain legal personhood. Slaves brought from Africa or those enslaved in the Americas were not legal persons and had absolutely no legal rights (the situation is murky w/r/t slavery practiced on indigenous people, but that's a separate discussion).

These older posts from u/sowser and u/sunagainstgold may help you parse out this difference, but the key points are:

• It was at no time in the Americas legal to keep a white person as a slave.

• Slavery and indentured servitude are fundamentally different institutions.

• There are various types of unfree labor, not all of which are equal.

https://www.reddit.com/r/AskHistorians/comments/9ymlxy/differences_in_indentured_servants_vs_slavery_in/

https://www.reddit.com/r/AskHistorians/comments/4d5c88/were_irish_ever_brought_to_north_america_as_slaves/

https://www.reddit.com/r/AskHistorians/comments/44a46l/are_there_any_records_of_white_people_being/