Six years later, but my teammate just pointed out to me: It's a unicode thing.

When you use Object Explorer (or its script), it's showing you the number of characters.

When you use sp_help, it's showing you the amount of space (number of bytes) needed.

If the column was varchar or char, for those 1 char requires 1 byte, so both of the above methods would show the same number (even though they have different meanings, characters vs bytes).

But when the column is Nvarchar or Nchar, for those 1 unicode char requires 2 bytes.

So, for example, your nvarchar column "MEMBER_LAST_NAME" can accept up to 35 unicode characters (see Object Explorer's info), which require 2x that: up to 70 bytes of space (see sp_help's info).