Mac OS Recovery: Disk Utility always partitions SSD
If you format your main internal disk from Recovery, Disk Utility will actually set the drive up ready to accept a new macOS. This will entail actually making 4 partitions, 3 of which will be nominally hidden from you.

If you don't need or want to see any of this 'under the hood' detail, you can set Disk Utility to only show Volumes, not all devices.

 Cmd ⌘   1  or View Menu > Show Only Volumes will do this for you.

if you really want to see everything that macOS hides from you, launch Terminal &amp; type diskutil list [this will not change anything, merely allow you to see it] - you'll see 'real' disks &amp; volumes, &amp; also synthesised ones which are virtual but necessary for the smooth operation of the system.

for example - 

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk1         1000.0 GB  disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1000.0 GB  disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            585.5 GB   disk1s1
   2:                APFS Volume Preboot                 21.2 MB    disk1s2
   3:                APFS Volume Recovery                509.3 MB   disk1s3
   4:                APFS Volume VM                      20.5 KB    disk1s4


Despite all this, all you will see in Disk Utility is either just Macintosh HD, or your drive's physical name [APPLE SSD SM056L Media] with [potentially an APFS container if your OS is new enough] &amp; Macintosh HD inside that.