Java Support Package Manager (JSPM) vs Software Delivery Manager (SDM)
Java Support Package Manager (JSPM) is used to apply support packages on deployed software components. JSPM detects the modified SAP software components and allows you to apply support packages to them. In other words JSPM is a tool provided by SAP which allows you to easily install the components and support packages.
Software Delivery Manager (SDM) is used for importing Java Support Packages. In other words SDM is a tool with which you can manage and deploy software packages received from SAP.
JSPM uses SDM for the deployment purpose. Justlike SPAM is used for importing ABAP Support Packages, Similarly Java Support Packages are imported using the Software Delivery Manager (SDM). JSPM is just like SPAM/SAINT.
The main difference between Java Support Package Manager (JSPM) and Software Delivery Manager (SDM) is JSPM which also indirectly connects to SDM tool but here we can apply software components all at one shot or at one go including kernel upgrade but in SDM we do the same things one by one.