What differences can I expect from my bass?
They are different and it all depends on what you like, what ever sounds good to you is good.
I am a beginner, but I've been playing fingered since the start, never even picked up a plec and I find my bass to be a sluggish, stiff piece of tree
Practise practise and practise, pick a album you like learn it and move on to another one. Stiff pieces of tree's can all be played
. Some are may be better than others. I am lucky enough to have a couple of nice stiff pieces of tree's
From what I've read the fretless are more fluid, with a better sound though often quieter?
A fretted can be played as fluid as anything its all in the skill of the player.