What is the difference between

[Algorta]

a baggy, ill-fitting T shirt as villified in the mumsy, frumpy threads, and the loose, slouchy T shirt which is always a suggested partner for skinny jeans in the "what do I wear with my skinnies?" threads?

Loose and slouchy will still fit you properly on the shoulders and neck line and will still have a shape to it. Baggy and scruffy t shirts are just big, shapeless tents that cover you but don't flatter you in any way. I think that's the difference.

Could be the neck...? A crew-necked baggy tshirt in plain cotton would look horrendous whereas something boat/slash-necked/off-shoulder in jersey or nicer slinky fabric might work.

One is a tenner from Bon Marche.

The other is £40 from White Company.

Perhaps the neckline? The former tends to be a mans / unisex t shirt with a high crew neck whilst a slouch, loose thing is usually differently cut with a more flattering neckline?

It's a minefield!

Agree about high, choking neckline and masculine, boxy shapes.
I prefer a slight scoop neck or v neck and also a thinner fabric, although not thin as in 'cheap'.

Also how you style it.
If the hem cuts at an unflattering spot for you (or any of us) this helps to ass to the frumpy factor. Some look better slightly tucked, and those gently rounded hem lines are a tad more chic in my opinion. They add a more feminine edge to the tee and seem to have a slimming effect (if you are arsed about such things).

And then there's how you style it. Accessories help a lot, too. Think thin scarf or necklace, bracelet, watch, etc.
It often helps, if you want to look chic, to wear more dressy shoes (good low heel courts or sandals, boots...) rather than work boots or trainers, of you see what I mean.

But that's just how I see it, so other people might not!

add to the frumpy factor, not ass! What a classy typo!