Titanium reacts with different chemicals and produces alloys of different colors, but its most common color is grey. Black titanium is another form of titanium alloy. On the other hand, carbide is generally always a gun metal grey.
Titanium is much more flexible than carbide. If hit with a great impact such as a car door, titanium material would bend out of shape from the event. Carbide on the other hand will shatter into many pieces on impact, which makes it generally safer for use in things such as wedding rings or other ring jewelry. The reason this is safer than titanium is that the flexibility of the metal makes it bend out-of-round on impact. This would affect the finger it was on, twisting it as well. The shattering carbide would not twist the finger out of shape if it was impacted.
Titanium is not as dense as carbide. It is more than forty percent lighter than stainless steel. Tungsten carbide is so much more dense, that it is ninety percent heavier than stainless steel. They are both very hard metals but carbide at its strongest is much harder than any titanium alloy.
When it comes to jewelry, hypoallergenic metals are preferable. Since some people are allergic to the cobalt found in some carbide jewelry, titanium is a better option. Titanium is considered a safe metal to wear for everyone who has concerns about allergies to the metal pieces they wear.