Your first example does seem to be too old. The passion fruit will mature on the vine. The type I have is yellow on the outside so it's easy to spot in the dark green foliage. If yours is the purple variety then it may be more difficult to tell. Examine your plant daily to see if any have come away from the plant. Sometimes they get stuck in the leaves and the vines making it more difficult to realize its ready.
If you shake the fruit you should be able to feel if there is juice in among those seeds.
This is a common sight here in the supermarkets. Women will shake each one before deciding to purchase.
The juice is clinging to the seeds and that's why a blender is the best way to go for removing them.