How to distinguish which following archetecture have lower coupling?

I have read a bound of articles about coupling which all without exception view it from a high perspective. They rarely elaborate it with real projects.

So, there is a specific question I met:

Simplified model as following:

• architecture 1

# m: module
      ---------                                                                 
      |context|
      ---------
     /  |    |  \
    /   |    |   \
----  ----  ----  ----
|m1|  |m2|  |m3|  |m4|
----  ----  ----  ----

• architecture 2

# m: module
# al: abstract layer
      ---------
      |context|
      ---------
      /       \
   -----     -----
   |al1|     |al2|
   -----     -----
  /   |       |   \
----  ----  ----  ----
|m1|  |m2|  |m3|  |m4|                                                          
----  ----  ----  ----

The questions is:

1. Which one have looser coupling than the other and why?
2. If answer is latter, then is there any relation between loose coupling and more layers?