what is the advantages of RS485 over LVDS?
maybe less devices required on RS485?....
If you are designing "both ends" it's up to you. I suppose you could make a chart to compare the characteristics of the two & costs of the two protocols.
In a "closed system", it's fairly common to use a non-standard "TTL" variation of RS-232 that uses a single-polarity signal level of +5V so no special drivers are needed.
Typically, you'll use a particular standard interface with some external device. RS-485 is used for temperature controllers, MIDI, and DMX. ...So if you are interfacing with one of those devices you'll need to comply with it's protocol.
I don't know where LVDS is standard. (I they they were using it for disk drives for awhile, but I doubt you are building a disk drive or a disk drive controller...)
P.S.
I've never used either one for a hobby project... We build RS-485 stuff where I work (And RS-422, and RS-232). I've used RS-232 quite a bit over the years but I don't ever remember ever building an RS-232 circuit. I have used SPI with the Arduino to interface with an LED driver chip because that's what the driver chip required.
how about topology?
i can see that in both configurations i can place recivers in the middle of the line....
or i missed something and over LVDS i can't place in the middle without termination of the impedance?..
what do you think about that?
RS485 will do 100's of metres in high noise environments, LVDS goes 10's of m in low
noise environments (but ~100 times less power consumption)
LVDS is normally used for gigabit rates over even shorter distances. RS485 might be
limited to 20MHz or so.
how about topology?
what is the difference?
LVDS is point to point unidirectional only AFAIK
RS485 is simplex bidriectional multi-drop.
You might find this document interesting: LVDS Application and Data Handbook
If you get a chance, take a look at "Figure 3–8" and its description.
School assignment?