Answer Description
Only full disk encryption will ensure the data is not readable by malicious users. The file system will not matter as their security features can be easily bypassed by using an operating system that ignores them. For example Linux operating systems can be configured to ignore NTFS permissions which would allow access to any data on the disk.
Wikipedia
Disk encryption is a technology which protects information by converting it into unreadable code that cannot be deciphered easily by unauthorized people Disk encryption uses disk encryption software or hardware to encrypt every bit of data that goes on a disk or disk volume It is used to prevent unauthorized access to data storageThe expression full disk encryption (FDE) (or whole disk encryption) signifies that everything on the disk is encrypted, but the master boot record (MBR), or similar area of a bootable disk, with code that starts the operating system loading sequence, is not encrypted Some hardware-based full disk encryption systems can truly encrypt an entire boot disk, including the MBR
Disk_encryption - Wikipedia, the free encyclopedia