This post shows you the difference between M.2 M and M.2 (B+M) in the aspect of plug (on SSD) and slot (on PC).
What's the Difference between Primary and Logical Partition
mSATA VS M.2: What's the Difference Between mSATA and M.2 SSD - MiniTool Partition Wizard
NVMe vs. M.2 Drives: Which SSD Is Right for You?
マルコ M.B.M.S イーシーグリーン 専門店の公式通販サイト
Overview of M.2 SSDs
NVMe vs M.2: Bus, Interface, and Protocol - MiniTool Partition Wizard
2 Types of M.2 SSDs: SATA and NVMe - Kingston Technology
Overview of M.2 SSDs
How To Distinguish the Differences Between M.2 Cards
マルコ M.B.M.S イーシーグリーン 専門店の公式通販サイト
NVMe vs M.2: Bus, Interface, and Protocol - MiniTool Partition Wizard
Compare EaseUS Partition Master vs. MiniTool Partition Wizard
マルコ M.B.M.S イーシーグリーン 専門店の公式通販サイト
HotTopStar Aluminum M.2 NVMe SSD Enclosure, USB 3.1 10Gbps USB-C NVME SSD Reader Adapter, M.2 NVME SSD Docking Station for NVME/SATA SSD with M and B+ M Key, Support 2230/42/60/80 External Hard Drive