Does ' /*+parallel(,4)*/ ' have better impact on query performance in comparison with simple parallel hint '/*+parallel(4)*/'?
Sure there is, but this may or may not be noticeable. We can not know this just by looking at your table definitions.
See below.

The first query does all operations in parallel with degree 4, including table accesses and joins:
Plan hash value: 2107928671
 
-----------------------------------------------------------------------------------------------
| Id  | Operation                         | Name                 |    TQ  |IN-OUT| PQ Distrib |
-----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                  |                      |        |      |            |
|   1 |  PX COORDINATOR                   |                      |        |      |            |
|   2 |   PX SEND QC (RANDOM)             | :TQ10004             |  Q1,04 | P-&gt;S | QC (RAND)  |
|   3 |    HASH JOIN OUTER BUFFERED       |                      |  Q1,04 | PCWP |            |
|   4 |     PX RECEIVE                    |                      |  Q1,04 | PCWP |            |
|   5 |      PX SEND HASH (NULL RANDOM)   | :TQ10002             |  Q1,02 | P-&gt;P | HASH       |
|   6 |       HASH JOIN OUTER BUFFERED    |                      |  Q1,02 | PCWP |            |
|   7 |        PX RECEIVE                 |                      |  Q1,02 | PCWP |            |
|   8 |         PX SEND HASH (NULL RANDOM)| :TQ10000             |  Q1,00 | P-&gt;P | HASH       |
|   9 |          PX BLOCK ITERATOR        |                      |  Q1,00 | PCWC |            |
|  10 |           TABLE ACCESS FULL       | CUSTOMER_INFO        |  Q1,00 | PCWP |            |
|  11 |        PX RECEIVE                 |                      |  Q1,02 | PCWP |            |
|  12 |         PX SEND HASH              | :TQ10001             |  Q1,01 | P-&gt;P | HASH       |
|  13 |          PX BLOCK ITERATOR        |                      |  Q1,01 | PCWC |            |
|  14 |           TABLE ACCESS FULL       | CUSTOMER_TRANSACTION |  Q1,01 | PCWP |            |
|  15 |     PX RECEIVE                    |                      |  Q1,04 | PCWP |            |
|  16 |      PX SEND HASH                 | :TQ10003             |  Q1,03 | P-&gt;P | HASH       |
|  17 |       PX BLOCK ITERATOR           |                      |  Q1,03 | PCWC |            |
|  18 |        TABLE ACCESS FULL          | BRANCH_INFO          |  Q1,03 | PCWP |            |
-----------------------------------------------------------------------------------------------
 
Note
-----
   - dynamic statistics used: dynamic sampling (level=2)
   - Degree of Parallelism is 4 because of hint

The second query accesses only CUSTOMER_TRANSACTION in parallel. Other tables are not accessed in parallel. Joins to CUSTOMER_TRANSACTION are however processed in parallel.
Plan hash value: 1958681835
 
-----------------------------------------------------------------------------------------------
| Id  | Operation                         | Name                 |    TQ  |IN-OUT| PQ Distrib |
-----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                  |                      |        |      |            |
|   1 |  PX COORDINATOR                   |                      |        |      |            |
|   2 |   PX SEND QC (RANDOM)             | :TQ10004             |  Q1,04 | P-&gt;S | QC (RAND)  |
|   3 |    HASH JOIN OUTER BUFFERED       |                      |  Q1,04 | PCWP |            |
|   4 |     PX RECEIVE                    |                      |  Q1,04 | PCWP |            |
|   5 |      PX SEND HASH (NULL RANDOM)   | :TQ10002             |  Q1,02 | P-&gt;P | HASH       |
|   6 |       HASH JOIN OUTER BUFFERED    |                      |  Q1,02 | PCWP |            |
|   7 |        PX RECEIVE                 |                      |  Q1,02 | PCWP |            |
|   8 |         PX SEND HASH (NULL RANDOM)| :TQ10000             |  Q1,00 | S-&gt;P | HASH       |
|   9 |          PX SELECTOR              |                      |  Q1,00 | SCWC |            |
|  10 |           TABLE ACCESS FULL       | CUSTOMER_INFO        |  Q1,00 | SCWP |            |
|  11 |        PX RECEIVE                 |                      |  Q1,02 | PCWP |            |
|  12 |         PX SEND HASH              | :TQ10001             |  Q1,01 | P-&gt;P | HASH       |
|  13 |          PX BLOCK ITERATOR        |                      |  Q1,01 | PCWC |            |
|  14 |           TABLE ACCESS FULL       | CUSTOMER_TRANSACTION |  Q1,01 | PCWP |            |
|  15 |     PX RECEIVE                    |                      |  Q1,04 | PCWP |            |
|  16 |      PX SEND HASH                 | :TQ10003             |  Q1,03 | S-&gt;P | HASH       |
|  17 |       PX SELECTOR                 |                      |  Q1,03 | SCWC |            |
|  18 |        TABLE ACCESS FULL          | BRANCH_INFO          |  Q1,03 | SCWP |            |
-----------------------------------------------------------------------------------------------
 
Note
-----
   - dynamic statistics used: dynamic sampling (level=2)
   - Degree of Parallelism is 4 because of table property