How can deleting similar number of rows result in very different log growth?
Way too much for a comment, but just to prove that the amount of data has a much bigger impact on how much gets logged, compared to simply the number of rows.

First, create a database, and back it up so we aren't in pseudo-simple:

CREATE DATABASE RLS;
GO
ALTER DATABASE RLS SET RECOVERY FULL;
GO
BACKUP DATABASE RLS TO DISK = 'c:\temp\rls.bak' WITH INIT;
GO
USE RLS;
GO


Now, create a skinny table and a wide table, and insert 2,000 rows:

CREATE TABLE dbo.skinnyTable(id int PRIMARY KEY);

CREATE TABLE dbo.wideTable(id int PRIMARY KEY,
  dt datetime2(7) NOT NULL DEFAULT SYSUTCDATETIME(), 
  n nchar(2000) NOT NULL DEFAULT USER_NAME(),
  x uniqueidentifier NOT NULL DEFAULT NEWID(),
  y uniqueidentifier NOT NULL DEFAULT NEWID(),
  z uniqueidentifier NOT NULL DEFAULT NEWID());

INSERT dbo.skinnyTable(id)
  SELECT TOP (2000) [object_id] FROM sys.all_objects ORDER BY [object_id];

INSERT dbo.wideTable(id)
  SELECT TOP (2000) [object_id] FROM sys.all_objects ORDER BY [object_id];


Backup the log twice:

BACKUP LOG RLS TO DISK = 'c:\temp\rls1.trn' WITH INIT;
BACKUP LOG RLS TO DISK = 'c:\temp\rls2.trn' WITH INIT;


With a clear log, let's delete half of each table (1,000 random rows):

;WITH cte AS (SELECT TOP (1000) * FROM dbo.skinnyTable ORDER BY NEWID())
  DELETE cte;

;WITH cte AS (SELECT TOP (1000) * FROM dbo.wideTable ORDER BY NEWID())
  DELETE cte;

SELECT AllocUnitName, log_rows = COUNT(*) 
  FROM sys.fn_dblog (NULL, NULL) AS l
  WHERE AllocUnitName LIKE N'%[ey]Table%'
  GROUP BY AllocUnitName;    


I get:

AllocUnitName                                     log_rows
----------------------------------------------    --------
dbo.skinnyTable.PK__skinnyTa__3213E83F83E76BF2    2008
dbo.wideTable.PK__wideTabl__3213E83FEFF3F638      14991


Clearly, there is much more log space required to delete the same number of rows from a wide table, when compared to a skinnier table.

As a logical extension, number and width of indexes can influence this difference as well. And I didn't even try LOB data, nor did I investigate the rows where AllocUnitName was NULL. The above alone demonstrates a 7X difference.