So both mods are focused around making building easier/less of a hassle.
Litematicas main feature is to display a overlay of a saved schematic over the landscape, and shows exactly how may of each block are required and left to collect. Within the overlay it also shows misplaced blocks very helpful in bigger redstone contraptions.
Tweakeroo, does does not have “that one main feature”. As the name implies its about tweaks, quite a bunch actually. And to be honest the one why I went to look for this specific mod back then, was a feature that allows to place block one of, as in if you have a water source in your farm and you want to place something on top you can do it. You look at the side of the block press the hotkey, some lines on the block apear and by moveing the crossair above the top section you can then place what ever block you have in your hand on top of that one.
Additionally to use all the features(including the one I mentioned above) of Tweakeroo the mod needs to be installed on the server as well, or either the QuickCarpet mod, or the Fabric Carpet + Carpet-Extra mods installed and the accurateBlockPlacement rule enabled.
Sincerely delimiter