What it means
Unauthorized activity means you did not approve the account transaction. Item Not Received means you intentionally paid for a purchase but the seller did not deliver it. PayPal places these under different Resolution Center reasons; a misdescribed item and subscription billing error have their own routes. The distinction affects what evidence is useful: account access and device history for unauthorized activity, order and shipping records for a delivery dispute.
A real-world example
A member orders shoes and receives nothing. They authorized the payment, so calling it account takeover would misstate the facts. In another case, a transfer appears while they were asleep and no household member or known automatic agreement explains it; unauthorized activity may fit.
What to do
Open the actual transaction in PayPal Activity, check automatic-payment agreements and household use, then select the reason that matches the event. Save the order, seller communications, tracking and case deadlines.
The distinction that matters
An invoice not yet paid is neither type of completed-charge dispute. A seller's failure to deliver does not prove an intruder signed in. Local purchase-protection eligibility and filing limits vary. PayPal's Romania help says an unresolved purchase dispute can be escalated to a claim and warns that an un-escalated dispute can close; follow the timeline shown in your specific case. If linked card or bank access is also affected, coordinate with that institution without hiding a parallel complaint.
PayPal Romania dispute reasons