Comment by em-bee

it's been a long time since i used screen. afaik screen had one session per process. you could switch processes by detaching from one and attaching to another. in tmux it's all one process, which allows you to create new sessions and switch them interactively and move windows from one session to another, or even have a window in more than one session. i can also see all windows from all sessions:

    (0)   - main: 6 windows
    (1)   ├─> 0: elvish-
    (2)   ├─> 1: elvish*: "[mosh] embee@foo:~"
    (3)   ├─> 2: elvish
    (4)   ├─> 3: elvish: "embee@bar:~"
    (5)   ├─> 4: elvish: "[mosh] embee@fedora:/etc"
    (6)   └─> 5: elvish
    (7)   - local: 6 windows (attached)
    (8)   ├─> 0: elvish
    (9)   ├─> 1: elvish-
    (M-a) ├─> 2: [tmux]*
    (M-b) ├─> 3: elvish
    (M-c) ├─> 4: elvish
    (M-d) └─> 5: elvish
    (M-e) - dev: 7 windows (attached)
    (M-f) ├─> 0: elvish*
    (M-g) ├─> 1: elvish-
    (M-h) ├─> 2: elvish
    (M-i) ├─> 3: elvish
    (M-j) ├─> 4: elvish