To be honest, i'd say that the Ti you are showing is way over priced (albeit it does have electric memory seats) but the Lusso looks to be a bit of a bargain for some reason. Maybe you'll find out why when you look at it. If it looks OK I'd snap up the Lusso if I were you.
Just to give you an idea of how over priced that Ti is, we just bought a 59 reg Sportwagon Ti 2.0 JTDM (not the 1.9) from an Alfa Main Dealer for £14k, albeit with the same mileage as that 2.4. Bear in mind that our car still has a year of manufacturers warranty left too.
In terms of differences between the Lusso and Ti, generally I think the normal main ones (I stand to be corrected) are wheels, lowered suspension and sports seats on the Ti. Think dials might be different too.
As has been said, normally the price difference wouldn't be that great.