I need to get new batteries for my Vx1000. I was going to get the standard Sony info-lithium NP-730H but I noticed at B&H they also have a brand called Bescor that is a 'Lead-acid' battery for the same price.

Here's their descriptions:
Bescor JB-5DNC Lead-Acid Battery Pack (8v, 4.2amps)

Sony NP-F730H, L Series, Info-Lithium, Battery Pack (7.2v, 3000mAh)

What is the real world difference with these?

Lead-acid is the same kind as found on cars, wheel chairs, etc.
http://www.batteryuniversity.com/partone-6.htm
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/leadacid.html

Biggest, heaviest/power delivered. Slow descharge (linear) vs. log on lithium.
Stick with lithium.(cell phones use LiIon not lead-acid and they're OK)
Li polymer deliver many times what the LiIon can due to "sponge-like" surface of electrolites vs plane surface.For the same reason, the power and charging time are supperior to anything previously sold.
http://www.allegromicro.com/techpub2/cadex/index35.htm
http://www.modelflight.com.au/kokam_lithium_polymer_lipo_battery.htm
Scroll down on the list to a 2000mA 7.2V, get two of those and you'll do just fine.

lead-acid are good when you need to deliver current FAST (high current drain). Like starting your engine car.
They're also discharging fast(er than Li-Ion) when not in use...
I'm using one to power an on camera light (50W).

4.2 amps vs 3 amps. Not knowing how many watts the VX1000 uses I can't accurately predict how much longer (probably more than an hour), but the Bescor SLA will def. allow you longer run times.

Prospective DIYers:
I actually use off the shelf 12V 7 amp radioshack SLA batteries ($20) + a custom wired DC<>DC convertor ($15 at any Walmart; brings 12v down to around 8Vish) all sitting in a small fanny pack (like the Bescor). Throw in a $25 6V/12V 1.5Amp automatic trickle charger from any automotive store (make sure it's automatic & no greater than 1.5Amp) and you're good to go. I get ~ 10-11 hours of runtime on little Canon Opturas and ~ 7-8 hours on a JVC HD1/HD10.