Wrong.
You would use Data Import Wizard if you need to avoid duplicates, as it allows to match records by criteria (Name, Email) and Data Loader doesn’t. Data Import Wizard and Data Loader both allow to import custom objects.
Data Import Wizard can import up to 50,000 records and Data Loader can import up to 5,000,000 records (for more than 5,000,000 records, you would use a third-party tool).

Right.
You would use Data Import Wizard if you need to avoid duplicates, as it allows to match records by criteria (Name, Email) and Data Loader doesn’t. Data Import Wizard and Data Loader both allow to import custom objects.
Data Import Wizard can import up to 50,000 records and Data Loader can import up to 5,000,000 records (for more than 5,000,000 records, you would use a third-party tool).
