hey chem nerds (espy/codaster)

All the properties are different, so I'd say just look at the industrial uses of each element. You might as well ask what differentiates the elements from Scandium to Copper

 

They have different atomic numbers for starters (which also means the way that electrons are found around the nucleus is different); use the new periodic table for better reference.

So, like this image shows that the each Lanthanide and each Actinide is actually different from members of its period and not all smooshed into one space like our old table shows.