I’m looking for something that’s like a plaindrome, except, it’s not the same back to front. It’s a sentence that, when you read it backwords, makes a completely different sentence. I’ve seen this in Russian - do any such sentences exist in English, and what are they called?
You might be thinking of a ‘semordnilap’ - which is a word or phrase that when spelled backwards creates a new word. (Semordnilap is palindrome backwards.)
Live/evil, dog/god, saw/was are semordnilaps.
An inartful example, but is this what you’re talking about:
You eat bugs?!
Bugs eat you?!
So basically, it’s a custom in Russia that’s completely reversed from the way they do things in America? 
It’s not what you’re looking for but …
There’s a famous line palindrome which reverses meaning backward despite that each line is the same. If you’ve never seen it, “The lost generation poem - you can reverse it” might be worth a look.
One thing to keep in mind is that you can always construct a palindrome from what the OP is talking about.
live/evil → evil live
dog/god → god dog
saw/was → was saw
This is actually one way I have always made palindromes. Once you memorize enough words that are different spelled backwards, it gets easy to make a palidrome:
evil dog saw rats, a star was god live…
etc
ETA: When I was a little kid I loved making palindromes, and I still have a sheet of paper where I tried to write down all of words I could think of that were different words spelled backwards. I cringe now, but I called them “semi-palindromic sub-structures” 
Convict a pet and feel a cop.
Yes, I googled, and this is what I mean. Anyone know of any sentences like this?
That’s not a poem, it’s a PEOM. It says so right in the headline.
desserts / stressed
cigar t / tragic
devil / lived
animal … lamina
dialer … re-laid
golfer … re-flog
kramer … remark
looter … re-tool
mooder … re-doom
recaps … spacer
re-cart … tracer
red leg … gelder
re-draw … warder
re-flow … wolfer
re-live … eviler
repaid … diaper
reward … drawer
romane … enamor
sinned … dennis
slipup … pupils
sorter … retros
spacer … recaps
spools … sloops
spoons … snoops
steels … sleets
strops … sports
teemer … re-meet
trader … re-dart
wolfer … reflow
diorama … amaroid
reified … deifier
re-level … leveler
re-lived … deviler
reviled … deliver
tressed … dessert
rewarder … re-drawer
You write sentence, Russia so different: so, Russia… sentence write you!
Not quite, I guess.
Wait, am I the only one that wrote an English sentence in a way that it has a different meaning backwards? Granted, my example is not that good, but at least it has a different meaning when read backwards. Shit, even the nouns turn in to verbs and the verbs turn into nouns, yet still make sense.
Here’s one a little more subtle in meaning but obvious in execution:
Hope is what defines man.
Man defines what is hope.
I think the OP is looking for what are called word-unit palindromes. Here are some links that contain examples:
http://www.fun-with-words.com/palin_word_palindromes.html
http://www.kmjn.org/notes/word_unit_palindromes.html
Here’s an entire poem that is a word-unit palindrome:
Love is This and This is Love
by
J.A. Linden
Darling, my love
Is great, so great;
Recalling Heaven’s calm above.
Fate is sweet this—
All after Fall!
Fall? After all,
This, sweet, is fate–
Above calm Heaven’s recalling.
Great, so great is
Love, my darling!
No, he’s not. He asked specifically for them NOT to be same back to front. He is not looking for palindromes. Let me quote:
It can’t be the same meaning backwards as it is forwards. It has to be wholly different.
Let’s try it again:
“Hope is what defines man”
An interesting thought. Quite deep even. But if you flip it back to front it has a completely different meaning:
“Man defines what is hope”
That’s a completely different thought, and also quite deep. That’s the key. It has to say something completely different back to front than it does front to back. It’s not a simple mirror like a palindrome, it is far more.
I wrote a short story that may be what the OP is looking for.
Backwards it read:
Mag lifted her eyes, looking up through lashes of feathers.
Was her Diablo
Rotti Largo
She knew
No solace
Marni Wallace
(my dearly departed)
“My eyes are open.”
Shackled
Her soft wings, newly emerged from the chrysalis
Diva Mariposa, glorious in repose
She has become
Gladly these weights on her heart and soul
She has suffered
For another
I made
A promise
And for what?
Tonight
Mag will be silenced
Forever
All we know
Is this
Just this once
Read it backwards.