It sort of depends on what you want to install, the two groups: sound-and-video and multimedia have slightly different packages:
$ sudo dnf groupinfo multimedia
Last metadata expiration check: 2:27:16 ago on Wed 02 Feb 2022 18:39:54 GMT.
Group: Multimedia
Description: Audio/video framework common to desktops
Mandatory Packages:
PackageKit-gstreamer-plugin
alsa-ucm
alsa-utils
gstreamer1-libav
gstreamer1-plugin-openh264
gstreamer1-plugins-bad-free
gstreamer1-plugins-bad-freeworld
gstreamer1-plugins-good
gstreamer1-plugins-ugly
gstreamer1-plugins-ugly-free
pipewire-alsa
pipewire-gstreamer
pipewire-pulseaudio
pipewire-utils
wireplumber
Conditional Packages:
ffmpeg-libs
gstreamer-plugins-espeak
pipewire-codec-aptx
qt5-qtwebengine-freeworld
sudo dnf groupinfo sound-and-video
Last metadata expiration check: 2:26:55 ago on Wed 02 Feb 2022 18:39:54 GMT.
Group: Sound and Video
Description: From CD recording to playing audio CDs and multimedia files, this package group allows you to work with sound and video on the system.
Optional Packages:
abcde
alsa-plugins-freeworld-lavrate
alsamixergui
amarok
asunder
audacious
audacious-plugins-freeworld
audacious-plugins-freeworld-aac
audacious-plugins-freeworld-mms
audacity
audacity-freeworld
avidemux
banshee
brasero
cdcollect
cdlabelgen
cdparanoia
cdrskin
denemo
devedeng
dragon
dvdauthor
dvdisaster
dvdstyler
dvgrab
easytag
festvox-bdl-arctic-hts
festvox-clb-arctic-hts
festvox-rms-arctic-hts
ffmpeg
gcstar
genisoimage
get_iplayer
gnome-sound-recorder
grip
gstreamer1-plugins-bad-nonfree
gtk-v4l
gtkpod
icedax
id3v2
irstlm
isomaster
juk
k3b
kid3
kmix
kodi
kover
kscd
lame
lame-mp3x
libquicktime-utils
lingot
live555-tools
lxmusic
mencoder
mikmod
milkytracker
mjpegtools-gui
mkvtoolnix-gui
motion
mp3gain
mpd
mpeg2dec
mpgtx
mplayer
mplayer-doc
mplayer-gui
multimedia-menus
mybashburn
mythmusic
mythtv-backend
mythtv-frontend
mythtv-setup
openfst-tools
opengrm-ngram-tools
paman
paprefs
parole
pavucontrol
pavumeter
picard
pipewire
pipewire-jack-audio-connection-kit
pipewire-pulseaudio
pitivi
pocketsphinx
pocketsphinx-plugin
qmmp
qmmp-plugin-pack
quodlibet
rakarrack
regionset
rhythmbox
rosegarden4
rtmpdump
smplayer
sonic-visualiser-freeworld
sound-juicer
soundconverter
soundtracker
sox
streamripper
sweep
tagtool
totem
traverso
tvtime
twolame
uade
ucview
v4l2ucp
vdr
vdr-burn
vdr-epgsearch
vdr-femon
vdr-mp3
vdr-mplayer
vdr-osdteletext
vdr-remote
vdr-skinsoppalusikka
vdr-streamdev-client
vdr-streamdev-server
vdrsync
vlc
volumeicon
vorbis-tools
wireplumber
wodim
xfburn
xine-lib
xine-ui
xmms
xmms-flac
xmp
Conditional Packages:
k3b-extras-freeworld
qmmp-plugins-freeworld
xmms2-freeworld
So sound-and-video also includes applications, but multimedia is more about the underlying codecs etc.
The first two commands of the third variant don’t install the full groups, they install a subset.
So, they’re all correct—depends on what you want to do. Some of us install packages as we need them incrementally, others prefer to install the full groups to get the whole superset of packages so they don’t have to worry about installing packages in the future.