One characteristic of the DNA replication is that the whole chromosome is replicated. On the contrary, only a portion of the DNA which codes for genes is transcribed into messenger RNA (mRNA).
Another characteristic is that the product of DNA replication is DNA and double-stranded. Transcription produces mRNA, which is a single-stranded molecule.
Another difference is that DNA replication is carried out by an enzyme called DNA polymerase, whereas transcription is carried out by an enzyme called RNA polymerase.
Finally, in DNA, adenine (A) pairs with thymine (T), while in RNA, thymine is replaced by uracil (U). Therefore, in mRNA A is paired with U.