Did you accept "default" settings for world generation? If so, then sharing the seed will allow people to play the same world. However if you've made changes to the world settings, then they will not get the same world you're playing. Even choosing "patchy" climate will produce a different world (I play with "patchy" climate, which is how I know this to be true).
@Blackbomber Seeds can be tricky. As @Vexxvididu mentioned, other settings in world customization can completely change the terrain. Not only do you need the seed, but also the world settings... AND sometimes mods too, as is the case for the River Mod. You might have better luck looking at ytubers using that mod, as you can see if their world appeals to you (some will share seeds and world settings).