Actually there is because, as I said in the original post, JKD does chi sao with the strong side forward, while WC does it in the basic horse stance (the one seen in Sil Lum Tao).
Yes and no. In JKD Bai Jong, it is pretty standard to be strong side forward. In Wing Tsun Bai Jong, depending on lineage (and individual practitioner), sometimes they are squared up and sometimes they are strong side forward as well. But this is only a guard position. Chi Sao is STICKING from contact; you are not sticking if you are in a shifted stance and can't reach your opponent with the back hand.
Chi Sao is an organic flowing thing, and one should not remain in a stationary position. There should be no fixed position. The Poon Sao position (the most common one seen that is used by the Yip Man branch) is only a starting position, and even that isn't set in stone. Often times, Chi Sao is initiated from no contact, so one can also train bridging and intercepting.
Honestly the difference I generally see between Wing Tsun and JKD Chi Sao is that a lot of JKD practitioners do not have the Wing Tsun foundation and lack the depth of skills and reflexes that comes from years of Chi Sao training, so they're just kinda winging it. Some JKD schools have absolutely no Wing Tsun in them whatsoever, and are basically just a stitched up MMA that's being called JKD, and their Chi Sao is sub-par for even beginner levels.
*Side note: The SNT stance is a training tool for beginners. You don't stand in YJKYM and fight. The farther you get in the system, the less you are restricted by the rules of the basics. If you see 2 high level practitioners, one WT and one JKD, sparring or Chi Sao'ing, it can be very difficult to tell them apart at times.
In higher level Chi Sao, legs (Chi Gerk) and even grappling comes into play. It's all fair game. It's good to be clear with your partner about what you wish to train and establish some rules before you engage though, so they don't get mad when you kick them or take them down.
I teach both Wing Tsun & JKD, and also do Escrima and Tai Chi. There are many overlaps in the drills/training (Chi Sao, Hubud, Tui Shou, etc), and they can all be used with or against each other.
BTW, nice to see you here Steve. I recognized the name in your website link. We chat on FB. I just posted a Chi Sao video in the Wing Chun section here the other day, check it out.