snippet post becomes large post

I was wondering how i could control the amount of info seen depending on each post.

I wanted to display a small image/thumnail and teaser text… then
reveal a bigger picture and much more text on the final post.

Is there a way to do this?

inside wordpress loop, i think i disabled this a long time ago a the beginning of my cms journey. where i made all thumbs really big.

…..or should i continue to use css to hide the thumb on the single.php page and the !more tag inside my posts to reveal more info…..
>>
archives.php
—————–
post title
text {thumb}
read more
—————–
post title
text {thumb inside div with class hide}
–read more–
—————–
post title
text {thumb inside div with class hide}
read more
—————
>>
single.php
posts id hide
text {thumb inside div with class hide}
big pictures
more content etc.
>>
style.css
div#hide .hide
{
display: none;
}

– now this works but, i cant figure why wordpress don’t do this –

Any Pointers please

and of course visit spartansafety.co.uk to see what i’ve done.