First of all, Congrats are making the decision to vape instead of smoke.
ok, lets start with the difference.
A provari or lavatube is very different that a blu. The provari/lavatube is considered a mod. They allow you to change the voltage. The battery is separate from the device. So, when the battery goes dead, you change the battery instead of replacing the device. They are also much larger and heavier. I own a provari and a volt (similar to a blu). The provari weighs 5 1/2 ounces where as the volt, which is like a cigarette, weighs about 1/2 ounce
An ego is a larger form of the "mini" It just allows you to go longer without charging the battery. I would not get an ego though, I would get a kgo. The ego is only 3.3v where as the kgo is 3.7
Now, for the mini, which is what a blu or greensmoke is. It is the size and shape of a cigarette. They need to be charged more often. Neither has a very good reputation on here, especially the blu. Many of us started with the blu because they have name recognition and really good marketing, but it is not a very good product, and its expensive
If you want a mini, which is sounds like you do, check out the Volt from smokeless image. Smokeless Image is the most recommended "mini" on the forum. Their battery lasts 2-4 hours as opposed to the Blu's 1 hour. The cartos last a long time and can be refilled several times (I have refilled mine 20-25 times) and dont burn easily. They are also reasonably priced. You can get a starter kit from smokeless image that is similar to the blu premium 100 ($90) for $65 and if you use coupon code YOURVOLT00 you can get 15% off bringing it to $55. In addition, Smokeless Image has a customer service that is second to none, which is why they are so highly recommended. I have a video on youtube that demonstrates the volt, but also goes over what you need to be successful, no matter what company you use. It also shows the volt x2, which is the same as a kgo, so you can get an idea of the difference.
http://youtu.be/ELM4QhceR7o
Sent from my iPad using Tapatalk HD