I think it was careless but not to the level f what it is clear Trump did.
She used a private server and some people emailed her top secret documents with the “top secret” part removed. She turned them over ASAP when asked.
Trump took the actual documents and did not turn them over when asked. Not only Top Secret but to the level of SCIF level, then when asked to return them he didn’t, then they subpoenaed him for them and he kept some…. They only got the documents back after getting a warrant and coming with authority to seize them.