Differences between avc1 and h264 during h264/AVC Video decoding

I have always wondered why the display format for some video decoding is h264, most of which are avc1.
I found on Microsoft's msdn when searching programming materials:
Http://msdn.microsoft.com/en-us/library/dd757808 (V = vs.85). aspx
Fourcc: avc1 Description: H.264 bitstream without start codes.
Fourcc: h264 Description: H.264 bitstream with start codes.

H.264 bitstream with start Codes

H. 264 bitstreams that are transmitted over the air, or contained in MPEG-2 program or transport streams, or recorded on HD-DVD, are formatted as described in Annex B of ITU-T rec. h.264. According to this specification, the bitstream consists of a sequence
Of network attached action layer units (nalus), each of which is prefixed with a start code equal to 0x000001 or 0x00000001.
H.264 video with a starting code is generally used for wireless transmission, wired broadcast, or HD-DVD. The start code of these data streams is 0x000001 or 0x00000001.

H.264 bitstream without start Codes

The MP4 container format stores H. 264 data without start codes. instead, each NALU is prefixed by a length field, which gives the length of the NALU in bytes. the size of the length field can vary, but is typically 1, 2, or 4 bytes.
This section roughly means that H.264 videos without a starting code are mainly stored in MP4 files. Its data streams start with 1, 2, or 4 bytes to indicate the length of data.

In the original article, "NALU" is simply the most basic unit in H.264 format and a data packet.

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