How do I know whether my Mac has a SSD or HDD installed without having to literally open my Mac?
PS. Is there anyway to know it from Disk Utility?
Alternatively you can run
system_profiler SPSerialATADataType or
system_profiler SPStorageDataType in Terminal which more or less gives you the same information
Apple Menu -> About This Mac -> System Report -> Hardware -> SATA/SATA Express
For my MacBook Pro (Early 2015) this showed the Serial-ATA Device Tree, from which I was able to get the model number for my SSD. This related question, How to get serial number from Mac hard disks? might help if you think you have an HDD.