Senryu or Haiku? And what's Tanka?

After you read the link, you'll understand why I often think I should have named this blog "Sorta Kinda Senryu." But, as is obvious from reading my earlier writing, I didn't really know what Haiku were, let alone Senryu. And I'd heard of Tanka before, but never tried to write one. I've only written a couple. Here's one I wrote this morning.

Blackberry flowers, 
white & delicate in the sun; 
milk thistle purple 
fringe on the green, thorny stalk; 
nothing ripe yet.

https://akitahaiku.com/what-are-haiku-senryu-and-tanka/