Are you wondering why the Visaton GmbH BF 37 8 Ohm speaker has different solder terminal shapes?
For clarification, please note that we have confirmed this with the manufacturer. As shown in the attached terminal change overview, both terminal designs are correct and acceptable.
The terminal design of the BF 37 models has been improved. This was implemented in order to provide additional protection for the loudspeaker’s supply wires against excessive stress in borderline areas. It also prevents solder from running too deeply into the supply strand due to the repeated soldering of connection cables and thus affecting the function of the speaker. This optimization has no mechanical effect on the installation of the speaker.
Please see the attached Document 
BF 37 - Overview terminal change 240117.pdf (405.3 KB)
Applicable Part Number
BF 37 8 OHM
2056-BF378OHM-ND