5 enemies in the same lane

Hard Carries will require a lot of items before they can be a significant threat, e.g. Anti-Mage will need to get a battlefury within 15 minutes, so that he can farm a Manta Style as fast as possible. Before he gets Manta, he's not as threatening as a Semi-Carry, say Queen of Pain or Juggernaut. Hard Carries will be the strongest players in the Late Game if they're farmed, usually because they either have the most powerful damage dealing items like Daedalus or Mjollnir, etc., or they have items that synergise with percentage based skills that get stronger as the game goes on, e.g. Sven 's God's Strength, Phantom Assassin's Coup de Grace.

Semi-Carries just need a few Lvls (usually lvl 6 to get their Ultimate) and a bit of Farm to be effective in the Early and Mid Game. However they will inevitably end up weaker then Hard Carries in the Late Game.

When looking at hero roles ingame, there is a 3 star ranking system on how "hard" they are at a role. By "hard" I do not mean difficult, but what the post above explained

they also, generally, don't have another role.. it is plain and simply Carry (with maybe escape, like AM, or durable for Spec). Where as ganker/semi carries, like Juggernaut or Night Stalker will have disabler/durable/ganker/carry/ as their options.

a full 5v5, the best and hardest carry is (ironically) probably Sniper.. he's DPS is so high and so far, with full items, he actually wastes his potential dps in the cast time of his ulti alone..

but no one EVER get's a fully farmed sniper :)

I still have the same problem :
What's the difference between support and lane-support ?
At first I thought I'd got it , but now that I checked I just saw that Earthshaker has become a lane-support too ! Why isn't venomancer a lane-support when earth is one ?
Or why isn't treant a support too ?(most lane-support s are supports too but jakiro and treant aren't !)
Is it about money ? like lane-supports don't need money ?

btw when should supports start warding river ? from the beginning ?
What about warding enemy's jungle in hard lane ?

Don't take the roles valve sets too seriously. Generally speaking a lane support is very good at controlling the lane, where as a support just generally buys wards, mek, etc. If Veno isn't a lane support and ES is, they just have it wrong, since ES has such big mana issues to be effective, where as veno is like the king of lane control.

so basically there isn't that much of a difference between them and normal supports can babysit too ?
btw when should supports start warding river ? from the beginning ?
What about warding enemy's jungle in hard lane ?

At beginning you want to ward enemy pull camp and usually 1 rune for your mid, sometimes enemy jungler camps or your jungle (before 30 sec mark). Then buy wards every cooldown (even if you don't have Boots of Speed, better buy Bracer and wards, instead of being selfish) and place them where it's needed (in your jungle to prevent ganks, in their jungle to gank them, on runes to have better control and avoid ganks, etc.).

About your first question - normal supports just can't always do it as good as babysitters like Silencer (who just force both enemies to sit under their tower). But when you start facing trilanes, there don't even exist such role as lane support, because 2 supports should make you get 0 exp from lane.

Silencer isn't mentioned as a Lane-Support ! where can I find list of lane-supports coz apparently the official list isn't that great .

Generally you should divide heroes into 4 sections, thats what I do:
- hard carry - take all farm possible, nearly always weak early game, but strong in late game
- semi carry (or ganker or snowballer) - person who dominate mid game without much farm and allow your hard carry to get stronger. If you plan to finish game very soon thats where semi carry can shine. With enough advantage over enemies he can easily carry game.
- initiator - a hero that prepare team fight for his team or counter initiate, usually with strong aoe ultimates like Black Hole
- support - heroes that dominate early to mid game and do everything to boost carry farm and gain advantage over enemy team with vision and ganks. Some supports can play with just Boots of Speed and Bracer, they are called hard supports. Some supports need more items to be fully effective.

Some heroes share roles, for example Faceless Void is one of hardest carries thanks to his skillset, but his ultimate Chronosphere is also great initiation tool.

If you'll understand each of these roles, it will help you understand what Dota is. I can make you list with specific roles of each hero and send if you want.

And thats how I understand Dota.

I know dota(have been playing it for years but just in a casual way) but I've never tried supports and now I want to learn the way to play with them and so this question struck me : What's the exact difference between Lane-Supports and Supports ?(I used to play Dota on Warcraft so I wasn't that familiar with words such as hard carry but I've always known the mechanics , heroes , items and stuff like that)
I've got many answers to this question and the one which I thought was true , was that Lane-Supports have some great buffs or heals . but now I see that Earthshaker is a Lane-Support too . The next answer that I thought was true was that Lane-Supports can control lanes well but then I checked and saw that someone like Venomancer who is great at controlling lanes isn't considered as a Lane-Support .

So what you're saying is that there isn't a big difference and I shouldn't pay that much attention right ?(I'm going to think this way since I really can babysit well with someone like Venomancer though he's not a Lane-Support)