Flash fiction example: In 700 words, a couple is having an argument in a coffee shop. The story shows their facial expressions, some of their exchanges, and how the situation escalates a bit and then cools down. For microfiction, 'The last petal fell. Hope died.' Here, microfiction is extremely condensed, just presenting a symbol (the last petal) and the associated feeling (loss of hope), while flash fiction has more space to show the development of a situation like the couple's argument.
Consider this for flash fiction: A young girl decides to run away from home. In about 800 words, we see her packing a small bag, leaving a note, and her initial adventures on the street, with some internal dialogue about why she's doing it. Now, for microfiction, it might be 'The soldier looked at the letter. Tears.' This microfiction captures a very brief, poignant moment without going into much backstory or development like the flash fiction example.
Sure. An example of flash fiction could be a 500 - word story about a man who finds a mysterious key in an old attic. He then goes on a short journey to figure out what the key unlocks, with a bit of description of his thoughts and actions along the way. For microfiction, it could be just 'She opened the box. Empty. Her heart sank.' This microfiction is much more concise and focuses on a single moment of discovery and the associated emotion.