The life cycles of Ectocarpus and Fucus are described as haplodiplontic and diplontic, respectively.

Haplodiplontic Life Cycle:
- The haplodiplontic life cycle is a type of life cycle exhibited by many algae, including Ectocarpus.
- In this life cycle, there are two distinct multicellular stages: a haploid gametophyte stage and a diploid sporophyte stage.
- The gametophyte stage produces haploid gametes (reproductive cells) through mitosis. These gametes are usually motile and can fuse to form a diploid zygote.
- The zygote then undergoes mitosis and develops into a diploid sporophyte, which is the second stage of the life cycle.
- The sporophyte stage produces haploid spores through meiosis. These spores are released into the environment and can develop into new gametophytes, completing the cycle.

Diplontic Life Cycle:
- The diplontic life cycle is a type of life cycle exhibited by many higher organisms, including Fucus.
- In this life cycle, there are two distinct multicellular stages: a haploid gametophyte stage and a diploid sporophyte stage.
- The gametophyte stage produces gametes through mitosis. These gametes are usually motile and can fuse to form a diploid zygote.
- The zygote immediately undergoes mitosis and develops into a multicellular diploid sporophyte, which is the dominant stage of the life cycle.
- The sporophyte stage produces haploid spores through meiosis. These spores are released into the environment and can develop into new gametophytes, completing the cycle.

Comparison:
- In the haplodiplontic life cycle, both the haploid and diploid stages are multicellular and independent.
- In the diplontic life cycle, the diploid sporophyte stage is the dominant stage, while the haploid gametophyte stage is relatively short-lived.
- The main difference between the two life cycles is the timing of meiosis. In the haplodiplontic life cycle, meiosis occurs in the sporophyte stage, producing haploid spores. In the diplontic life cycle, meiosis occurs in the sporophyte stage, producing haploid gametes.

In summary, the life cycle of Ectocarpus is haplodiplontic, while the life cycle of Fucus is diplontic.