All questions and problems regarding LXDE components including LXSession, LXAppearance, GPicView, Leafpad, LXTerminal, Xarchiver, LXNM to be discussed here.
For PCManFM questions, please ask in the dedicated forum below.
Two obvious differences are,
the Exec key has an environment variable assignment in it
the Path key has some garbage [$e] and refers to $HOME
I do not remember whether lxpanel supports environment variable assignments in the Exec key. I know this was added to lxsession at some point.
(This is the problem with having all of these pieces as separate little applications. They all have different features and bugs.)
I do not remember whether lxpanel supports the Path key, and even if it did, yours has a value outside anything that the Freedesktop standard defines.
The [$e] and the reference to $HOME are not standard.
I no longer have LXDE and I cannot try this myself.
If you want to experiment with editing your .desktop file, you need to log out and in, because lxpanel reads the .desktop file once when it loads the launchbar.