SPF and DSPF stand for the same thing - its an acronym for "Detailed Standard Parasitic Format".
DSPF (or SPF) file is the output of extraction tool (StarRC, QRC/Quantus, CalibrePEX / XRC, F3D,...) - a text file containing post-layout netlist.
It contains information about design elements (MOSFETs, diodes, BJTs, resistors, capacitors, inductors,...) as well as parasitic elements (usually Rs and Cs, sometimes - Ls and Ks (self- and mutual inductances)).
Being fully SPICE-compatible, DSPF file format contains a lot of additional useful information (in the form of SPICE comments) - such as coordinates of nodes and parasitic elements, layers, instance pins, ports, subnodes (fracture points of polygons for R extraction), etc. etc.
DSPF is an industry standard format used for transistor level post-layout analysis - such as SPICE simulation, IR/EM analysis, timing analysis, etc.
Unfortunately, information about DSPF format is sparse, and also this format is not as well defined and not as strict as, for example SPEF format (SPEF is a gate-level post-layout RC netlist format, used for place-and-route designs for timing, IR/EM, etc.).
Check with Calibre documentation on how to generate DSPF format from XRC.