What is the difference between 广阔，宽阔，宽广 and 辽阔?
广阔 vast; wide; spacious; expansive; extensive; broad:


广= broad 阔= wide

广阔 (broad) mostly describe: 


space - e.g 广阔空间 (broad space)  
territory - e.g.  广阔领土 (broad territory) 
area - e.g. 广阔面积 (broad area) 



  宽阔 broad; wide; roomy; spacious 


宽= spacious 阔= wide

宽阔 (spacious) mostly describe:


space  - e.g. 宽阔空间 (wide space); 宽阔房间 (spacious room)
object - e.g 车身宽阔 (the car is wide) 



  宽广 broad; extensive; spacious; vast:


宽= spacious 广 = broad

宽广(expansive) mostly describe:


space - e.g 宽广空间 (expansive space)
area - e.g 地方宽广(area is expansive)



  辽阔 vast; extensive


辽= distant = 阔= wide

辽阔 (vast) mostly describe:


space  - e.g.  辽阔空间 (vast space)
territory - e.g.  辽阔领土 (vast territory )
area - e.g. 地方辽阔 (area is vast)


Maria Efremova wrote:


  Is there any difference in usage between 广阔 and 辽阔?  


广阔 is more general, It can be used to describe area in a grand scale, for example: '广阔的宇宙'(wide universe) but it can also be used to describe area in much smaller scale, for example:  '广阔的足球场' (wide football field) 

It can also be used metaphorically. For example 心胸广阔 (forgiving). 

辽阔 is more specific. It is exclusively for describing area in a grand scale. (area that cover vast distance and require long time to travel) 

辽 itself means 'distant' (far away in time or space) 

you can say '辽阔的宇宙' (vast universe) but you cannot say '辽阔的足球场' (vast football field) because it is too small in scale.