What are usually the differences between a light to medium ball vs a medium ball?

Can I use both as my first ball out of the bag to bowl on THS? Which one is better with a fresh lane? Which one is better when the lanes break down?

I'm a lefty who bowls outside, so usually I don't relay to much on the oily parts of the lanes. I like a ball with a good length, that can have a good read of the front and the mid lane and with a good backend reaction with a strong hook at the end, kind of like a hockey stick shot with a delayed/late hook.

I'm thinking about buying a light to medium ball in order to use it on my league and be able to bowl at least the first two games with the same ball, since I'm a lefty my lane conditions doesn't change as much as for a right handed, but I also want to know if buying a medium ball is the same or not. For example (Tribal Fire vs Melee Jab)

Any thoughts? Thanks!

Tribal Fire is pretty strong. I can easily be used to start on THS is you have any revs

I'm a low rev guy, average to low speed, so I was wondering if I should start with a medium, with a medium to heavy or with a light to medium ball on a typical THS, usually the way I bowl (lefty, outside, between the 4 and 8 board, nice length, strong backend) is most of the time drier, so I was wondering what option should be better, a light to medium or a medium...

Really depends on your specs and style. The Motiv stuff is a bit stronger than advertised. I really like the venom shock for ths. But that's me

On the left side, I really don't see enough break down to worry about needing a light option.  Usually 1 versatile medium ball can work for a normal 3 game set.  For MOTIV, I think the balls down the middle column of the ball guide ( http://www.motivbowling.com/resources/ball-guide.html ) would be most versatile.  Many have recommended the Sigma Sting to me, and I'm about to get one.  This may be what you are looking for also.  Plus there is a discount offer ( http://www.motivbowling.com/motivnation/news-events/2014-11-01/sigma-sting-and-cruel-intent-rebate.html ) this month on this ball.

Which ball do you throw that is burning up?

You'll have to decide if you want versatile, or a defined late motion - you can't get both.

What surface do you have on your current bowling balls?

The Paranormal is supposed to be very early rolling, I can see this one burning early.

The Ruckus is not supposed to be especially long either.

The Wicked Siege should be a good medium ball.  The goal should be to get more length than this one.

What surface do you have on your current bowling balls?

The Paranormal is supposed to be very early rolling, I can see this one burning early.

The Ruckus is not supposed to be especially long either.

The Wicked Siege should be a good medium ball.  The goal should be to get more length than this one.

On the Paranormal (Sanded) I have 1000, on the Ruckus and the Wicked (both polished) I have 2000 and in the Gryphon I don't know since it was a gift from someone who used it for a couple of games, but I guess its almost the same surface as the Ruckus and Wicked...

What is really confusing me is what ball would help me more overall, and what ball can I use more, this is gonna be the first ball with my own layout, I read the Dual Angle Ball Layout and I want to choose everything by myself, so I'm between the Primal Rage, The octane and the Tribal Fire... I'm so confused right now 

With lower revs, there is not a huge difference in lines/angles to play that will give good carry.  Inside too much just doesn't work.  I'm guessing that you are playing outside where there is not a lot of oil to start with - then using what little there is up by playing your sanded ball first.  Maybe starting with a matte (4000) or shiny ball with more backend will allow you to play the outside oil line for more than 1 game.

You will have to decide for yourself if you think that you want to try getting a better ball to start off with (Primal Rage or Sigma Sting) or if you like your current balls well enough and just want to fill the medium/light space (Octane or Tribal Fire).

Just my thoughts - not an expert by any means - maybe others can add more....