"i thought that buying Titanium gear is all about saving weight but when you have aluminum gear that weighs less than what advantages are left for the titanium?"
Actually, no. Ti is about atomic weight 48. Al is about 27. Ti is about 60% more dense than Aluminum (unalloyed.) It is quite ductile (takes dents well and pulls wire easily) but, for cooking pots is alloyed with Aluminum resulting in a stiffer pot. Indeed, I fell on one and cracked it trying to unbend it.
Aluminum is LIGHTER than Titanium by a considerable margin. However, once it is alloyed with Aluminum (usually about 2/3 ti) it is a LOT stiffer. Making a pot of the same strength means that the pot will be roughly 1/2 as thick. So, it CAN be lighter. As I remember, only the older BPL pots were this thin, though. If you believe the old myth about Aluminum being bad for you, it doesn't matter, since it has Aluminum in it. It doesn't corrode with acidic foods much, though (tomato sauces, fruit fillings, etc.) Generally, the lightest aluminum pots will be lighter than Ti pots, but for generally manufactured stuff, weights of the lightest Ti pots are about the same as an Aluminum pot of the same capacity. Cost is about 8-10 times as much for Ti. A $5 1.3L grease pot(Al) will cost about $40-50 in Ti.
Ti does not conduct heat very well. With the Al added, it is better, but still it does not like to transfer heat as readily as AL. Gold, copper, and Al do far better. Roger C and I had quite a discussion on this about three or four years ago. He pointed out that the difference was only about 1-2% for thin walled camping pots, but I think he did not add for sideways conductance (along the material.) Anyway, Ti has a way of burning water. Aluminum does not. 2-4F over the same time period (to 200F or about boiling) seemed somewhat significant to me. Roger thought not. Thicker pots, of course, do worse.
Olicamp Hard Anodized XTS Pot (1-Litre) has a built in heat exchanger for use with any stove. I do not have one yet (1 liter is a bit small, I prefer a 1.3 liter) but would like to get one some day. Around $25-30 US. It weighs about 7oz but may be worth it in fuel savings (I go through about 2.75oz of alcohol or 1oz of WG per day.)