I have both well, kinda, I've got what Trog used to sell as the "Ultimate" kit which was the standard 901 SD with an adapter for the 801. I have owned the SD for a few months had have had the stick for close to a month. Initially there was no difference in performance, vapor, taste, throat-kick wise. There still isn't a difference to me in those areas, as there shouldn't be, they are both 3.6 to 3.7 devices using the same atomizer with a manual switch.
The seperating factors are:
1. Batteries
2. Durability
3. Cost
Let's look at these individually,
Batteries - the Screwdriver roughly gets twice the battery life as the stick. It is important to note that with both the screwdriver and the Janty Stick the batteries will begin loosing life within a few weeks. You will notice they don't last as long as when you first purchased them, you will need to replace these batteries just as you do any other PV(although at a cheaper cost and less frequently). The Janty Stick uses a built in usb passthrough so when you have USB or 110 available and within reach you can charge and vape at the same time.
Durability - The Janty Stick is made of plastic, the SD is made of aluminum. They both use a manual switch. The switch on the Janty Stick looks to be prone to separating from the body and is held by adhesive. You can stick it back on there but if it separates once it will separate again. Some Sticks have a leaking issue (this may be caused by the rubber tip cartridges), while any PV will leak, it seems more detrimental to the stick because it can collect in there and become messy. The SD switch is durable but will wear out eventually and need to be replaced which Trogg can either send you directions or you can send it back to him for repair. The SD switch will break if you drop the SD and it lands on the switch. The Atomizer connection on the SD if dropped with an atomizer connected could become damaged if it lands on the atomizer end. The Janty Stick if dropped could fall apart and need to be reassembled as Cellmeister shows here:
http://www.e-cigarette-forum.com/forum/jantyusa/20724-cracking-open-janty-stick.html
Cost - The Janty Stick is $80 and the Screwdriver is $160. Batteries for the Screwdriver cost as low as $2 and as high as $10, no e-cig retailers carry the batteries so you will need to order them from other retailers online such as
www.dealextreme.com or
Welcome to BatteryJunction.com - Our prices won't leave you drained! The Stick uses the same batteries as e-cigars and are available from several e-cig retailers. They can be purchased for as low as $1.50 and as high as $4. The Janty Stick comes with a 6 month warranty.